Tonsillectomy is accompanied by 7 to 14 days of pain. We entered 36 patients into a double blind placebo controlled study with dantrolene sodium, lioresal to evaluate modification of tonsillectomy pain and analgesic requirements after tonsillectomy. Patients were randomly assigned either dantrolene or lioresal or placebo orally four times a day for 5 days postoperatively. On a standardized questionnaire the patients recorded pain, activity level, analgesic requirements and side effects. We conclude that there is no significant differences in subjective pain or analgesic requirements between 3 groups. The muscle spasm is not the only factor of tonsillectomy pain. There is the association of other factors: nerve endings, individual sensitivity, local products of inflammation. In conclusion to control tonsillectomy pain we must use drugs with different action.