Clonidine (1.3 micrograms/kg) was administered to 62 control and 55 depressed patients free of psychoactive drugs for at least 7 days and fasted overnight. Growth hormone (GH), pulse, blood pressure and sedation were measured every 15 min for 1 h before and 2 h after clonidine infusion. GH response did not differ significantly between control and depressed subjects overall or when divided by sex. The systolic hypotensive and sedative responses were blunted in depressed subjects compared with controls; these effects appeared to be secondary to residual antidepressant drugs since the differences were only significant for those depressed subjects with short drug-free intervals. No differences between depressed subjects and controls were seen in diastolic hypotensive or bradycardic responses and no differences in GH, cardiovascular or sedative responses were found between endogenous and non-endogenous depressed subjects.