To investigate the potential effect of Nicergoline, an alpha-adrenolytic drug, on negative symptoms in patients suffering from chronic schizophrenia, we administered this compound to 20 male chronic schizophrenics. Patients were previously maintained on long-term neuroleptic (NL) medication. Neuroleptic treatment was discontinued for 12 days, patients were then treated with 30 mg Nicergoline per day. Under NL (A), after 12 days NL-withdrawal (B), after 15 (C) and 30 (D) days Nicergoline treatment clinical ratings (BPRS and AMDP) and stimulation with clonidine (0.002 micrograms/kg body weight) were carried out. Norepinephrine (NE), epinephrine (E), and human growth hormone (HGH) were measured before and after application. Seventeen patients finished the study, 3 dropped out. Some ratings on the AMDP and BPRS scales showed an improvement. However, this improvement was only weak and accompanied by a worsening in other subscores. The withdrawal-induced decrease in NE serum levels continued after 15 days NIC, followed by an increase after 30 days. HGH response to clonidine stimulation was only attenuated after 30 days NIC. Epinephrine, blood pressure and heart rate showed no significant changes throughout the entire study. Our data suggest that NIC in the dosage applied shows no clear and pronounced alpha-2-adrenolytic effects and no specific clinical benefits for chronic schizophrenics. Further investigations are required to evaluate its effect on alpha-1-adrenoceptors.