Six parkinsonian patients received a constant subcutaneous infusion of 60 micrograms lisuride per hour in the abdominal region for 2 hours. Plasma levels of the unchanged drug were measured by radio-immunoassay. During infusion, a steady state plasma level of 0.78 +/- 0.19 ng/ml was achieved. After discontinuation of the infusion, concentrations declined with a half-life of 1.4 +/- 0.4 hour. The total clearance of lisuride was 20 +/- 6 ml/min/kg. Due to the low interpatient variability of plasma levels, a good control of clinical effects is to be expected.