We have examined the expression of acidic fibroblast growth factor (aFGF) in the rat ovary using reverse transcription-polymerase chain reaction (RT-PCR). RNA was extracted from hypothalami of adult rats and whole ovaries or isolated granulosa cells of gonadotropin-primed immature rats. The RNA was reverse transcribed and amplified by PCR using oligonucleotide primers specific for rat aFGF. RNA from hypothalamus or whole ovary yielded a dominant DNA band corresponding in size to the aFGF segment spanned by the two primers (301 base pairs, bp). Its identity with the aFGF sequence was confirmed by restriction enzyme analysis. The aFGF product was also obtained from two of four granulosa cell RNA preparations; when obtained, the intensity of the signal was less than that from whole ovary, indicating that the major sites of aFGF expression are outside the granulosa layer.