The study was taken up to assess the effect of bypass fat supplementation on the performance of anoestrous Swamp buffalo heifers and cows maintained at Network Project on Buffalo Improvement (Swamp), College of Veterinary Science, Assam Agricultural University, Khanapara, Guwahati, Assam, India. Efficacy of bypass fat in the treatment of anoestrus was studied on the basis of genital changes, level of some of the blood biochemical constituents and oestrus response. Twenty five per cent of the anoestrous heifers and 25 per cent of anoestrous cows treated with bypass fat + minerals + injectable phosphorus showed vulvar oedema and congestion, uterine tone and ovarian activity within 30 days of treatment. Level of serum leptin and IGF-1 was significantly higher in anoestrus cows on day 30 of treatment and the values were 4.11 ± 0.16 ng/ml for leptin and 74.11 ± 1.26 ng/ml for IGF-1 as against 3.40 ± 0.09 ng/ml leptin and 61.99 ± 4.87 ng/ml IGF-1 recorded at day 0 of treatment. Treatment of anoestrous heifer with bypass fat alone or bypass fat + minerals + injectable phosphorus for a period of 30 days resulted in increased serum oestrogen and progesterone level on day 30 of treatment indicating a positive effect of bypass fat in addressing anoestrous in buffalo heifers. In the anoestrous buffalo cows bypass fat treatment for a period of 30 days either alone or fortified with minerals and injectable phosphorus had no effect on serum oestrogen and progesterone concentration. Bypass fat treatment resulted in 37.50 per cent oestrus response in anoestrous buffalo heifers and 50.00 per cent oestrus response in anoestrous cows.