PAGE 1
000 A000000 03/31/2016
000 C000000 0000884121
000 D000000 N
000 E000000 NF
000 F000000 Y
000 G000000 N
000 H000000 N
000 I000000 6.1
000 J000000 A
001 A000000 TEKLA LIFE SCIENCES INVESTORS
001 B000000 811-6565
001 C000000 6177728500
002 A000000 100 Federal Street, 19th Floor
002 B000000 BOSTON
002 C000000 MA
002 D010000 02110
003 000000 N
004 000000 N
005 000000 N
006 000000 N
007 A000000 N
007 B000000 0
007 C010100 1
008 A000001 TEKLA CAPITAL MANAGEMENT LLC
008 B000001 A
008 C000001 801-000000
008 D010001 BOSTON
008 D020001 MA
008 D030001 02110
010 A000001 STATE STREET BANK AND TRUST CO.
010 B000001 85-85003
010 C010001 BOSTON
010 C020001 MA
010 C030001 02111
012 A000001 COMPUTERSHARE TRUST CO. N.A.
012 B000001 85-113400
012 C010001 CANTON
012 C020001 MA
012 C030001 02021
013 A000001 DELOITTE & TOUCHE LLP
013 B010001 BOSTON
013 B020001 MA
013 B030001 02110
015 A000001 STATE STREET BANK & TRUST CO.
015 B000001 C
015 C010001 BOSTON
015 C020001 MA
015 C030001 02110
015 E010001 X
018 000000 Y
019 A000000 Y
PAGE 2
019 B000000 4
019 C000000 TEKLAFUNDS
020 A000001 NATIONAL FINANCIAL SERVICES CORP.
020 B000001 04-2785576
020 C000001 46
020 A000002 J P MORGAN SECURITIES INC
020 B000002 13-3224013
020 C000002 43
020 A000003 JEFFERIES & CO.
020 B000003 95-2622900
020 C000003 21
020 A000004 MORGAN STANLEY & CO.
020 B000004 13-2655990
020 C000004 15
020 A000005 BANK OF NEW YORK MELLON
020 B000005 13-5160382
020 C000005 13
020 A000006 WEDBUSH MORGAN SECURITIES, INC.
020 B000006 95-2495390
020 C000006 11
020 A000007 MIZUHO CORPORATE BANK LTD.
020 B000007 13-5624234
020 C000007 7
020 A000008 STIFEL NICOLAUS & CO. INC.
020 B000008 43-0538770
020 C000008 6
020 A000009 BANK OF AMERICA SECURITIES
020 B000009 95-4035346
020 C000009 5
020 A000010 BARCLAYS BANK
020 B000010 06-1031656
020 C000010 5
021 000000 183
022 A000001 STATE STREET BANK AND TRUST CO.
022 B000001 04-1867445
022 C000001 855601
022 D000001 0
022 A000002 BANK OF NEW YORK MELLON
022 B000002 13-5160382
022 C000002 2331
022 D000002 0
022 A000003 J P MORGAN SECURITIES INC
022 B000003 13-3224013
022 C000003 2040
022 D000003 0
022 A000004 MAGELLAN DIAGNOSTICS, INC.
022 C000004 0
022 D000004 2000
022 A000005 STIFEL NICOLAUS & CO. INC.
022 B000005 43-0538770
022 C000005 1900
PAGE 3
022 D000005 0
022 A000006 BANK OF AMERICA CORP.
022 B000006 95-4035346
022 C000006 1869
022 D000006 0
022 A000007 JEFFERIES & CO.
022 B000007 95-2622900
022 C000007 0
022 D000007 1864
022 A000008 GENOMEDX BIOSCIENCES, INC.
022 C000008 1400
022 D000008 0
022 A000009 ILLUMINOSS MEDICAL, INC
022 C000009 575
022 D000009 0
022 A000010 BIOCLIN THERAPEUTICS, INC.
022 C000010 433
022 D000010 0
023 C000000 866522
023 D000000 3864
024 000000 N
025 D000001 0
025 D000002 0
026 A000000 N
026 B000000 Y
026 C000000 N
026 D000000 Y
026 E000000 N
026 F000000 N
026 G010000 N
026 G020000 N
026 H000000 N
027 000000 N
028 A010000 0
028 A020000 0
028 A030000 0
028 A040000 0
028 B010000 0
028 B020000 0
028 B030000 0
028 B040000 0
028 C010000 0
028 C020000 0
028 C030000 0
028 C040000 0
028 D010000 0
028 D020000 0
028 D030000 0
028 D040000 0
028 E010000 0
028 E020000 0
PAGE 4
028 E030000 0
028 E040000 0
028 F010000 0
028 F020000 0
028 F030000 0
028 F040000 0
028 G010000 0
028 G020000 0
028 G030000 0
028 G040000 0
028 H000000 0
030 A000000 0
030 B000000 0.00
030 C000000 0.00
031 A000000 0
031 B000000 0
032 000000 0
033 000000 0
035 000000 0
036 B000000 0
038 000000 0
042 A000000 0
042 B000000 0
042 C000000 0
042 D000000 0
042 E000000 0
042 F000000 0
042 G000000 0
042 H000000 0
043 000000 0
044 000000 0
045 000000 Y
046 000000 N
047 000000 N
048 000000 0.000
048 A010000 0
048 A020000 0.000
048 B010000 0
048 B020000 0.000
048 C010000 0
048 C020000 0.000
048 D010000 0
048 D020000 0.000
048 E010000 0
048 E020000 0.000
048 F010000 0
048 F020000 0.000
048 G010000 0
048 G020000 0.000
048 H010000 0
048 H020000 0.000
PAGE 5
048 I010000 0
048 I020000 0.000
048 J010000 0
048 J020000 0.000
048 K010000 0
048 K020000 0.000
049 000000 N
050 000000 N
051 000000 N
052 000000 N
053 A000000 N
054 A000000 Y
054 B000000 N
054 C000000 Y
054 D000000 N
054 E000000 N
054 F000000 N
054 G000000 N
054 H000000 N
054 I000000 N
054 J000000 Y
054 K000000 N
054 L000000 N
054 M000000 Y
054 N000000 N
054 O000000 N
055 A000000 N
055 B000000 N
056 000000 N
057 000000 N
058 A000000 N
059 000000 Y
060 A000000 Y
060 B000000 Y
061 000000 0
062 A000000 N
062 B000000 0.0
062 C000000 0.0
062 D000000 0.0
062 E000000 0.0
062 F000000 0.0
062 G000000 0.0
062 H000000 0.0
062 I000000 0.0
062 J000000 0.0
062 K000000 0.0
062 L000000 0.0
062 M000000 0.0
062 N000000 0.0
062 O000000 0.0
062 P000000 0.0
PAGE 6
062 Q000000 0.0
062 R000000 0.0
063 A000000 0
063 B000000 0.0
066 A000000 Y
066 B000000 N
066 C000000 Y
066 D000000 N
066 E000000 N
066 F000000 N
066 G000000 N
067 000000 N
068 A000000 N
068 B000000 N
069 000000 N
070 A010000 Y
070 A020000 Y
070 B010000 Y
070 B020000 N
070 C010000 N
070 C020000 N
070 D010000 Y
070 D020000 N
070 E010000 N
070 E020000 N
070 F010000 Y
070 F020000 N
070 G010000 Y
070 G020000 N
070 H010000 Y
070 H020000 N
070 I010000 N
070 I020000 N
070 J010000 Y
070 J020000 Y
070 K010000 Y
070 K020000 N
070 L010000 Y
070 L020000 Y
070 M010000 Y
070 M020000 N
070 N010000 Y
070 N020000 N
070 O010000 Y
070 O020000 N
070 P010000 N
070 P020000 N
070 Q010000 N
070 Q020000 N
070 R010000 Y
070 R020000 N
PAGE 7
071 A000000 83740
071 B000000 96506
071 C000000 417589
071 D000000 20
072 A000000 6
072 B000000 115
072 C000000 601
072 D000000 0
072 E000000 0
072 F000000 2256
072 G000000 51
072 H000000 0
072 I000000 28
072 J000000 58
072 K000000 31
072 L000000 21
072 M000000 76
072 N000000 0
072 O000000 0
072 P000000 0
072 Q000000 0
072 R000000 58
072 S000000 58
072 T000000 48
072 U000000 0
072 V000000 0
072 W000000 64
072 X000000 2749
072 Y000000 0
072 Z000000 -2033
072AA000000 0
072BB000000 10138
072CC010000 0
072CC020000 57121
072DD010000 0
072DD020000 0
072EE000000 32767
073 A010000 0.0000
073 A020000 0.0000
073 B000000 1.6600
073 C000000 0.0000
074 A000000 1
074 B000000 3859
074 C000000 0
074 D000000 8606
074 E000000 24844
074 F000000 332657
074 G000000 0
074 H000000 0
074 I000000 0
074 J000000 149
PAGE 8
074 K000000 0
074 L000000 92
074 M000000 215
074 N000000 370423
074 O000000 0
074 P000000 348
074 Q000000 0
074 R010000 0
074 R020000 0
074 R030000 0
074 R040000 308
074 S000000 0
074 T000000 369767
074 U010000 20123
074 U020000 0
074 V010000 18.37
074 V020000 0.00
074 W000000 0.0000
074 X000000 198
074 Y000000 0
075 A000000 0
075 B000000 432323
076 000000 17.94
077 A000000 N
078 000000 N
080 C000000 0
081 B000000 0
082 B000000 0
083 B000000 0
084 B000000 0
086 A010000 437
086 A020000 8987
086 B010000 0
086 B020000 0
086 C010000 0
086 C020000 0
086 D010000 0
086 D020000 0
086 E010000 0
086 E020000 0
086 F010000 0
086 F020000 0
087 A010000 TEKLA LIFE SCIENCES INVESTORS
087 A020000 87911K100
087 A030000 HQL
088 A000000 N
088 B000000 N
088 C000000 N
088 D000000 N
SIGNATURE LAURA WOODWARD
TITLE TREASURER