The clomipramine (CMP) distribution in 12 regions of rat brain was investigated 2 and 7 days after subcutaneous minipump implantation. The results of serial blood samplings during 7 days indicated that steady-state CMP serum levels were achieved from experimental day 2. The regional CMP distributions in the brains were uneven on both the 2nd and 7th experimental days. On both test days the CMP concentrations were higher in the cerebral cortex and hippocampus than those in the other regions, and those in the cerebellum and bulbus olfactorius and septum were lower. When the serial fluctuations of the CMP levels were examined in 12 brain regions, there were significant differences between days 2 and 7 in the following four regions: the anterior basal ganglia, hypothalamus, bulbus olfactorius + septum and amygdala.