Evidence for the binding of a calcium antagonist, [3H]nitrendipine, to human brain membranes was obtained. This binding was saturable, specific and of high affinity with a dissociation constant (Kd) of 0.62 nM in the prefrontal cortex and 0.82 nM in the caudate. The maximal numbers of binding sites (Bmax) in these areas were 57.5 and 32.3 fmol/mg protein, respectively. [3H]Nitrendipine binding to membranes from 27 regions in the post-mortem human brains was measured. The highest levels of 0.5 nM [3H]nitrendipine binding were seen in the cerebral cortex, amygdala and thalamus, and levels in the midbrain, cerebellum and pallidum were considerably lower.