Radiant heart(RD) and Meperidine(MEP) have been used to suppress postanesthesia shivering. However their efficacies to date have only been assessed by observation of visible shivering. We measured the effects of RH and MEP on oxygen consumption (VO2), minute volume(VE) in sixteen otherwise healthy patients(two groups of eight each) shivering after general anesthesia. RH successfully supressed visible shivering in all patients and was associated with significant decrease in VO2(16% of baseline) and VE(13% of baseline, p<0.05). In the reshivering patients, the effect of RH on VO2 was less than initial RH therapy owing to sustained invisible shivering. MEP suppressed visible shivering in seven patients and was associated with 13% decrease in VO2. In conclusion, RH and MEP are effective methods of reducing the elevated oxygen consumption by shivering.