Анотация: This study was aimed at evaluating the effect of three different light regimens on serum leptin, lipid profile, abdominal fat pad triglyceride content and adiposity of broiler chickens. For this purpose, 60 one-day-old broiler chickens (Cobb 500) were distributed in three light-proof controlled rooms (20 chicks per room). All birds were reared under continuous light until 1 week of age. Then the chicks were treated as follows: 1. Continuous lighting (CL) programme (23L:1D), 2. Non intermittent restricted lighting programme (NIL) (6L:18D from day 7 to 28, 23L:1D from day 29 to 42) and 3. Intermittent lighting programme (IL) (1L:3D cycles). At day 42 of age, sera were collected from fasted chicks of each group and serum leptin levels and lipid profile were assayed. Then, abdominal fat weight and triglyceride content were evaluated. Feed intake, body weight and feed conversion ratio (FCR) were determined at the end of the experiment. Body weight of chickens reared under IL was slightly higher than other groups, but there was no significant difference among groups. Use of IL and NIL lighting schedules improved FCR. IL and NIL lighting programmes significantly reduced abdominal fat percentage in comparison with CL programme (P<0.05). Serum leptin levels were significantly higher in CL group in comparison with other groups (P<0.05). Blood leptin levels were positively correlated with abdominal fat pad size or adiposity in all groups. Serum triglyceride, cholesterol, lipoproteins (HDL, LDL,VLDL) and abdominal fat pad triglyceride content of birds under different photoperiod schedules did not differ significantly (P>0.05). In conclusion, use of IL and NIL programmes can enhance production efficiency and decrease adiposity and serum leptin level with no appreciable effect on abdominal fat pad triglyceride and serum lipid profile in broiler chickens