The short-term efficacy of dihydro-alpha-ergocryptine (DEK), a hydrogenate ergot derivative with dopamine (DA) agonist properties was evaluated in 20 L-dopa (LD) stable responder parkinsonian patients by a 6-month double-blind randomized, placebo-controlled study. A motor improvement was found only in DEK-treated patients at mean daily doses of approximately 40 mg, ranging from 15 to 60 mg. The side effects never required the withdrawal of the drug or changes in its schedule. The authors demonstrate the efficacy and the good tolerability of DEK as a new DA agonist drug that can be added to LD in the treatment of parkinsonian patients.