Sheep have more than 900 different breeds. Therefore their physiological characteristics including ovulation rate and fecundity, vary greatly. A group of genes effect the ovulation rates of sheep. Studies showed that there are two structural genes and one receptor gene that are the members of the transforming growth factor beta TGFP family and their names arc BMP-1B. BMP-15 and GDF-9 respectively. In this article we focus on to review the data of the BMP-1B, BMP-15 and GDF-9 gene mutations that effect sheep's ovulation rate and fecundity.