The startingpoint is the evidente for relationship between tentral 5-HT and the occurence of certain types of depressions. Symptomatology, etiology and course are described. The average duration of the illness of the patients was about nine years and they were treated with alle common antidepressive drugs before, but in vain. With the 5-HT precursor L-5-hydroxytryptophan in a dosage that varies from 50 to 800 mg daily, combined with 150 mg Carbidopa, about 50 % of the patients showed an amazing recovery, without side effects. Though it is an open study, it affirms the results from the controlled studies which made clear the antidepressant potency of L-5-HTP.