There are three histological layers within the rat olfactory tubercle: plexiform, pyramidal, and polymorphic. We have assayed dopamine-sensitive adenylate cyclase in homogenates of frozen sections cut parallel to these layers. Consecutive sections (16 micrometer) were homogenized in groups of 6. Every seventh section was stained with toluidine blue to monitor the depth and orientation of the plane of section. I report the laminar distribution of dopamine-sensitive adenylate cyclase at two locations within the tubercle where the local topographies are quite different from one another. In the caudomedial tubercle where the parallel alignment of the neuronal layers is clearest, there is a marked gradient in the activity of dopamine-sensitive adenylate cyclase. Its distribution corresponds very closely to the distribution of pyramidal cell bodies and their dendrites in this region of the olfactory tubercle.