In this study, the hemodynamic and neurochemical effects of lisuride, a dopamine agonist with serotoninergic properties, have been evaluated in de novo parkinsonian patients and in elderly subjects with mild cognitive impairment. Blood pressure (BP), heart rate (HR), and urinary catecholamine (CA) fluctuations throughout the 24-h cycle were monitored before and during lisuride therapy along with BP, HR, and plasma CA responses to the tilt-table test. Lisuride (1.2-2.4 mg/day) administered in an open-type 15-day study was capable of decreasing the urinary CA excretion and norepinephrine plasma levels in parkinsonian patients. In some cases, the cardiovascular response to standing was impaired. Lower doses of the drug (0.15 mg/day), administered to elderly patients in a double-blind parallel group vs. placebo study, did not induce any change in cardiopressor responses but decreased the 24-h urinary excretion of epinephrine. These results suggest the importance in both conditions of detecting early stages of alterations in cardiopressor homeostatic processes before therapy with DAergic drugs is initiated.