BACKGROUND: Although post-anesthetic shivering may be a temporary phenomenon, it leads to detrimental effects such as increased oxygen consumption, hypoxemia, and difficulty in monitoring. Doxapram is a relatively new treatment for post-anesthetic shivering, but there have been few reports about its minimum effective dose. The purpose of this study was to find the minimum dose of doxapram which would show an antishivering effect. METHODS: Sixty patients who had developed post-anesthetic shivering were divided into six groups of ten patients each. The groups were divided into a control group, which received normal saline, and the doxapram groups, which received five different doses of doxapram (0.15, 0.2, 0.5, 1.0, 1.5 mg/kg). The antishivering effect (2, 5, 10, 15 minutes after treatment), blood pressure, heart rate and temperature were compared among the groups. RESULTS: There was a significant difference in antishivering effect between the group which received normal saline and the groups which received doxapram; however, there was no significant difference within the groups which received doxapram. CONCLUSIONS: We conclude that the dose of doxapram required to achieve an antishivering effect is much less than that currently in use.