Bisphenol-A (BPA), an environmental estrogen, has adverse effects on the male reproductive tract in mammals and birds. In ovo administration of BPA at high doses have been reported to cause the left gonad to form an ovotestis in fowl and quail. However, there are no studies on morphometric effects of in ovo administration of BPA on testis. Therefore, the aim of present study was to investigate the morphometric effects of in ovo administration of low and high doses of BPA on hatched testis. For comparative purposes, well characterized synthetic estrogen diethylstilbestrol (DES) was also examined. Chicken eggs were treated (injection volume 100 mu l/egg) on day 4 of incubation before the gonads start to differentiate. Doses were 67 (low BPA group) and 134 (high BPA group) mu g BPA/g egg, and 0.02 (low DES group) and 0.2 (high DES group) mu g DES/g egg. Sertoli cell and germ cell numbers were determined by stereological methods. Our results indicated that low doses of BPA had no negative effects, on the contrary it was at least increased germ cells proliferation in avian similar to mammals counterpart. However, as doses were titrated upwards, negative effects emerged on seminiferous tubules of testis.