Serum and cerebrospinal fluid (CSF) cortisol were measured by radioimmunoassay in male talapoin monkeys living in social groups. The slopes of the regressions between cortisol in the two compartments were significantly less in dominant than either the most subordinate males or those of intermediate rank. Furthermore, the dominants’ CSF also contained proportionately more cortisol than was predicted from the overall regression analyses of the groups of which they were members. There was no difference in the proportion of ‘free’ cortisol (that is, not bound to serum proteins) between the serums of dominant or subordinate males. These findings point to an association between social status and the distribution of cortisol between blood and CSF in these mo