Trials were conducted to evaluate the influence of vitamin B2, ascorbic acid and melatonin on the reproductive performance of cross ewes during summer. A total of 42 healthy mature cross ewes (3/8 Finnish X 5/8 Rahamani) was randomly allocated into 4 groups: the first group (G1) served as control (n=11) without any treatment. The second group G2 (n=10) and third group G3 (n=11) were injected daily with 2 cm (15mg) of vitamin B2 and ascorbic acid intramuscular, respectively. Ewes in the fourth group G4 (n=11) received double subcutaneous injections daily of 0.5mg melatonin at 8 A.M and 16 P.M at the dorsal surface of ear. All treated groups (G2,G3,G4) received 6 cm of zinc chloride (1gm) and chromium (2.5mg) per os once per week. All animals were checked for the onset of oestrus two times daily using an intact ram. Fertility parameters including lambing rate, frequency of single, twin, triplet and sex ratio (male/female) were recorded. Blood samples were collected weekly and sera were separated for determination of progesterone. Laparoscopic examinations were carried out pre and post-treatment (3weeks). Follicular development and ovulation rates were observed among different groups. Results indicated that, ascorbic acid treated group had a significantly (P>0.05) decreased mean interval from treatment to oestrus as compared to control group (15.73±1.83 Vs. 22.64 ± 2.50, respectively). A remarkable improvement in the lambing rate in vitamin B2, ascorbic acid and melatonin treated groups than that in the control one (80.00, 90.91, 90.00 Vs. 72.72%, respectively). The highest proportion of ewes bearing single lamb was observed in ascorbic acid group (100.00%). Incidence of lamb mortality found only in vitamin B2 treated group (triplet) in one ewe. Sex ratio was higher in melatonin group (4.0) than those in control, ascorbic acid and vitamin B, treated groups (0.80, 1.00 and 1.75, respectively). The ovulation rate was significantly (P>0.05) elevated in melatonin treated ewes than that in vitamin B2 and control groups (1.60±0.16 vs. 1.20 ± 0.13 and 1.14 ± 0.00, respectively). The follicular development did not vary among different groups. In conclusion, vitamin B, ascorbic acid and melatonin have a beneficial effect on the reproductive performance of ewes during summer.