The aim was to determine the expression of Bax in germ cells of rats with unilateral experimental cryptorchidism, and to evaluate the role of apoptosis in germ cell loss. Twenty-one prepubertal rats were randomly subdivided into three groups after the execution of the left cryptorchidism model. Group 1 (n=8), group 2 (n=6) and group 3 (n=7) rats were killed at the end of the first, second and third month, respectively. Bax expression was assessed in Sertoli cells, spermatogonia and spermatocytes by immunohistochemistry. Percentages of Bax expression in spermatocytes and spermatogonia were decreased in the left testicles in the 2nd and 3rd months compared to results obtained in the 1st month (p<0.05). Percentage of Bax expression in the left testicles of group 1, at the level of both spermatogonia and spermatocytes was higher than that in the right one (p<0.05). However, in groups 2 and 3, the higher Bax expression on the left side was only seen in the spermatocytes (p<0.05). In all groups, the mean weight of the left testicle was lower than that of the scrotal counterpart where the difference was significant only in groups 1 and 3 (p<0.05). The weight of the left and right testicles was increasing with time. In this model of cryptorchidism, the affected testis had a decreased weight compared to the normal one. Based on the increased Bax expression, we think that apoptosis may play a role in the germ cell loss.