The aquatic environment is the ultimate destiny for chemical contaminants of anthropogenic origin. Present study is an attempt to assess the alterations induced in the ovarian follicular composition of adult female zebrafish (Danio rerio) exposed to environmental estrogenic contaminants (EECs) at a concentration lower than environmental recorded levels for long-term (80 days) in the laboratory. Adult zebrafish (n=20) were maintained in a medium containing environmental estrogens such as, 17α-ethynil estradiol (EE2) (5 ng/L and 10ng/L) or diethylstilbestrol (DES) (5 ng/L and 10ng/L) or bisphenol (BPA) (5 ng/L and 10ng/L). Corresponding negative controls were maintained for comparison. On the 81st day the fish were sacrificed, body and ovarian weights were recorded and ovaries were processed for histology, sections of 3 μm thick were cut and stained with hematoxylin and eosin. All the follicles were counted and quantified from alternative serial sections. Growing follicles were classified into 6 stages based on their functional status and size. Atretic follicles were counted separately. The results reveal that exposure of female fish to estrogenic compounds even at a very low dose for long-term leads to increased body weights and size, with an increase (P<0.05) in the gonadosomatic index (GSI). There was a significant decrease in the number of previtellogenic follicles in all EEC exposed groups. Vitellogenic follicle number was greater in EE2 group compared to other EEC exposed groups, while atretic follicles were relatively greater in DES and BPA groups. It is suggested that long-term exposure to EEC even at lower concentrations alters follicular composition of adult zebrafish ovary.