The aim of this randomised, double-blind study was to investigate the usefulness of intravenous nefopam, clonidine or placebo in preventing shivering in patients undergoing conscious sedation for interventional neuroradiological procedures. A total of 101 patients were prospectively enrolled and assigned to one of three groups to receive nefopam, clonidine or placebo. The overall incidence of intra-operative shivering was significantly lower in patients treated with nefopam than in those treated with clonidine or placebo (2/32 (6%) vs. 11/38 (29%), p < 0.02; 2/32 (6%) vs. 24/31 (77%), p < 0.0001, respectively). The number of patients who required ephedrine infusions to maintain a mean arterial pressure of 100 mm Hg was higher in the clonidine group than in the nefopam and placebo groups (18/38 (47%) vs. 5/32 (17%), p < 0.05; 18/38 (47%) vs. 6/31 (19%), p < 0.05, respectively). We found that both nefopam and clonidine significantly lowered the rate and severity of shivering during interventional neuroradiological procedures. Fewer patients in the nefopam group than in the other two groups required vasoactive drugs.