Follicular and luteal phases of estrus cycle of Tapri and mixed goats under semi intensive management system. In order to get insight to understand the mechanism of steroidogenesis and study of various phases of estrus cycle in highly prolific Tapri goats of Sindh, in first phase an attempt was made to determine the length of various phases of estrus cycle of Tapri breed and its comparison with cross breed goats during three estrus cycles. Total ten healthy adult cycling goats (five from each breed) were maintained at the departments of animal reproduction and livestock management, FAHVS, SAU, Tandojam. Vaginal cytology method was used as marker to determine the status of estrus cycle. It was found that mean length of estrus cycle in Tapri and cross breed goats were 21.32±0.26 and 21.2±0.56 days, respectively, both the longest (22.2±0.67 days) and shortest (20.4±0.66 days) duration of estrus cycles length were found in cross breed. The length of follicular phase including the estrus was 1.48±0.07, 1.34±0.01 days and during proestrus period it was 2.98±0.01 and 3.20±0.1 days in Tapri breed and cross breed respectively, similarly, during luteal phase the length of metestrus and diestrus were in Tapri versus cross breed goats were 3.25±0.14 vs 3.28±0.6 and 13.59±0.10 vs 13.28±0.4 days, respectively. (Am J Transl Med 2019. 3:151- 158).