Cerebral microvessels were separated and prepared from human brain cortex by albumin floatation and glass bead filtration. The binding of a specific β-adrenergic antagonist, (125I) iodohydroxy- benzylpindolol, to the microvessel preparation was characterized by high affinity, saturability, and stereospecificity. The presence of specific β-adrenergic receptor sites in human cerebral microvessels supports the hypothesis of adrenergic regulation of the function of cerebral microvessels.