Carbon paste electrodes modified with beta -cyclodextrin have been investigated for the DP voltammetric determination of the tricyclic antidepressants - imipramine, trimipramine and thioridazine. Host-guest interaction was studied and experimental conditions of the working procedure were optimized. The accumulation ability of beta -cyclodextrin leads to detection limits down to nanomolar concentrations for 120 s accumulation. The electrode was applied to the determination of imipramine and thioridazine in pharmaceuticals.