Bats are the most diverse and successful group of mammals exhibiting many adaptive specializations.Chiroptera shows great variations in the reproductive stage, even the closely allied species exhibit different breeding habits. It is important to study the reproductive organ that is ovary in respect with the interstitial cells, because the interstitial cells with the help of LH of pituitary produce a hormone androgen. That means interstitial tissues are developed as a gland having steroidogenic activity. The immature ovary of Megaderma lyra lyra showed the small bundles of few interstitial cells in stromal region. In inactive ovary of Megaderma lyra lyra, interstitial cell bundles observed 48 ± 5 and number of interstitial cells observed in each bundle are 5 to 9. In the active ovary of Megaderma lyra lyra the bundles of interstitial cells observed 56 ± 5. Number of interstitial cells in each bundle in Megaderma lyra lyra observed 10 to 20. Pregnant ovary of Megaderma lyra lyra showed extroverted carpus luteum, atretic follicles and destructed interstitial cells. In the immature ovary of Rousettus leschenaulti numerous interstitial cells observed in the stromal region. In the inactive ovary of Rousettus leschenaulti, interstitial cell bundles observed 41 ± 5 and number of interstitial cells observed in each bundle are 5 to 7. In active ovary of Rousettus leschenaulti the bundles of interstitial cells observed 47 ± 5. And number of interstitial cells observed in each bundle are 5 to 10, So it is concluded that the interstitial cells in the active ovary is more steroidogenic than inactive ovary