A randomised crossover study in eleven diabetic patients with arteritis compared the effects of nicergoline (2,5 mg i.v.) or placebo on haemodynamic and metabolic parameters after exercise tests. Haemodynamic modifications after effort following placebo administration were typical: raised systolic blood pressure, and increased heart rate and myocardial oxygen requirements (systolic BP x heart rate). Modifications after similar effort following nicergoline involved an increase in systolic B.P. only, heart rate and myocardial oxygen requirements remaining unchanged. Blood lactic acid levels after effort and treatment were significantly higher (p. less than 0.01) than after effort without treatment. Overall metabolic and haemodynamic results demonstrate an increase in effort tolerance in diabetic patients with arteritis after nicergoline, this having been previously observed in healthy subjects.