Z-1-(4-Bromophenyl)-1-(3-pyridyl)-3-dimethylaminopropene dihydrochloride hydrate (zimelidine; H 102/09), a newly developed bicyclic substance, was tested in a pilot study for its clinical effect in 10 female patients with a depressive syndrome. Zimelidine inhibits the 5-hydroxytryptamine (5-HT) reuptake more potently than does chlorimipramine. The action on the norepinephrine reuptake is weaker compared with imipramine, also the cardiotoxic and anticholinergic effects are lower. Zimelidine was administered for 20 days in a daily dose of 150 mg. A significant (p less than 0.05) improvement from the beginning of the treatment to the 15th day was demonstrated in Hamilton rating scale and a self-rating scale (von Zerssen). Nevertheless, the zimelidine treatment had to be discontinued between the 15th and 18th days in 3 patients, because of agitation symptoms. The antidepressant action in some patients justifies the performance of controlled studies.