Distribution in rat tissues of citalopram, a potent and specific inhibitor of neuronal 5-HT uptake was uneven. The blood serum level of the drug did not reflect its distribution in the brain tissue and in the spinal cord. Prolonged administration of citalopram enhanced its blood serum, brain and spinal cord AUC values and slowed down its elimination from all investigated tissues. In contrast to imipramine, citalopram penetrated easily to the spinal cord.