The in vitro effect of bisphenol A (BPA) on ovarian steroidogenesis of the longchin goby (Chasmichthys dolichognathus) was investigated. Oocytes taken during the maturing phase (vitellogenic, fully vitellogenic or germinal vesicle breakdown stage) were incubated with BPA (100 ng/mL) in the presence of exogenous precursor $^{3}H-17alpha;hydroxyprogesterone;(^{3}H-17alphaOHP).$ Steroids were extracted from the media and the isolated oocytes, and the extracts were separated and identified by thin layer chromatography and gas chromatography-mass spectrometry. The identities of the major metabolites were progestogens $[17{alpha}-hydroxy,20{alpha}-dihydroprogesterone;(17{alpha}20{alpha}OHP);and;17{alpha}-hydrxy,20{eta}-dihydroprogesterone;(17{alpha}20{eta}OHP),$ androgens [androstenedione (A4) and testosterone (T)] and estrogens [estrone $(E_1);and;estradiol-17{eta}(E_2)].$ BPA treatment inhibited production of estrogens in all the maturing phases and progestogens in the germinal vesicle migrating stage. Percentage yield of estrogens was decreased with increased yield of androgens. In conclusion, BPA had an inhibitory effect on the conversion of $^3H-17alphaOHP$ to estrogens and progestogens. These results demonstrate that BPA can act either estrogenic or anti-estrogenic effects.