Clinical surveys revealed higher incidences of anestrous due to inactives ovaries in buffaloes in comparison to cattle, and this affects production potential in the form of huge economic losses. In the search for fruitful remedies for anestrous, many hormonal as well as non-hormonal preparations have been tried by several workers, and each has its own merits and demerits.Application of insulin to modulate reproduction in livestock is a fairly recent development. Recombinant growth hormone and positive energy balance altered the ovarian activity with increase in circulatory IGF-1 and insulin as well intrafollicular IGF-1 concentration.The exogenous insulin was found to enhance steroidogenesis and folliculogenesis by modulating action of follicular growth factor system and steroidal hormones.