A cDNA encoding the potential activin beta C subunit was produced from human testis RNA using reverse transcription and PCR and then used as a probe in Northern blot analysis of poly(A)+ RNA. A transcript of approximately 1.8 kb was evident in human ovary, placenta and testis samples. A transcript of this size was also detected in adult rat caput and cauda epididymis, and adult and day-15 testis and adult spleen, while adult liver contained a single transcript of approximately 2.1 kb. Poly(A)+ RNA from primary spermatocytes but not from round spermatids contained the 1.8 kb activin beta C mRNA. These findings highlight the need for further studies to determine the physiological role(s) of activin beta C in a wide variety of tissues.