We report the results of the first large-scale questionnaire surveillance on the clinical use of pit viper antivenom in tertiary care centers in Japan. The questionnaire surveillance was conducted over a period of 3 years (April 2006 to March 2009). Completed questionnaires were received from the tertiary care centers of 108 (49.3%) medical institutions. In that period, 574 cases of pit viper bites, including 2 severe cases, were reported. Antivenom was administered in 44% of the cases of pit viper bites, and of these cases, 2.4% had adverse reactions but no severe symptoms. Approximately half of the clinicians indicated that antivenom was effective. Antivenom was recognized to be safe; however, the remarkable finding was that although the severity of treated cases was unclear, some clinicians reported using cepharanthine as the first choice of treatment for pit viper bites.