Autoradiographic methods were used to investigate locations of hormone concentrating cells in the CNS of Xenopus laevis. Both male and female frog brains contained cells. Four major hormone uptake sites were identified: the anterior preoptic area, the ventral infundibular nucleus, a dorsal tegmental area of the medulla and a presumptive motor nucleus of cranial nerves IX-X. The distribution of labelled cells was very similar for male and female brains. Available information on these testosterone uptake sites in anurans indicates possible roles in gonadotropin regulation and reproductive behavior.