Cytological and histological characteristics of normal and freemartin gonads have been studied in 45-, 60-, and 90-day bovine fetuses during gonadotropin-induced multiple pregnancy. In both sexes of 45-day fetuses the second proliferation of germinal epithelium was not developed whereas the primary tunica albuginea was well developed. Fetal testes showed higher cell activity than fetal ovaries. Mitotic activity seemed slower in 60-day freemartin gonads than in normal fetal ovaries. The chromosomal stages prophase, metaphase, anaphase and telophase corresponding to oogonia were less numerous than in normal fetal ovaries. The cytological appearance of freemartin gonads in 60-day fetuses was unaffected by the ratio of male: female fetuses. The freemartin gonad was characterized by an irregular distribution of cortex and primary tunica albuginea. In the ovaries of 90-day fetuses the last chromosomal stage observed in the oocytes was the pachytene stage. The first establishment of primordial follicles was observed.