The histomorphological studies on ontogeny of Peyer's patches in jejunum of 20 buffalo fetuses ranging from 11.5 cm CVRL (80 days) to 100 cm CVRL (299 days) were conducted. The fetuses were categorized into three groups based on their curved crown rump length (CVRL). The fetuses of gestational age from 11.5 cm CVRL (80 days) to 28 cm CVRL (136 days) were devoid of typical jejunal lymphoid patches. However, at 32 cm CVRL (145 days) aggregates of 2 to 3 lymphocytes were observed arranged linearly in submucosa of jejunum Elongated to oval lymphocytic aggregations were observed in submucosa at 54 cm CVRL (195 days) that formed primordia of lymphoid follicle. The presence of darkly stained lymphocytes was also observed in the intestinal villi above the aggregates at this stage. At 70 cm CVRL (231 days), a number of round, pear shaped developing lymphoid follicles were encountered. At 100 cm CVRL (full term), completely developed lymphoid follicles of different shapes i.e., oval, pear shaped and square shaped follicles were present that were arranged in a single row on the anti-mesenteric part of jejunum. The dome of lymphoid follicle was completely formed at this age by invading the jejunal villi that formed arcs over it. Therefore, the present study suggests that the jejunal Peyer's patches started its development at mid-gestational age and become completely developed in the fetuses that reached upto full term just before birth. Thus these jejunal Peyer's patches generates immune response by sampling foreign antigens entering the lumen and play a crucial role in terms of generating mucosal immunity.