The antinausea and antivomiting effects of delta-9-tetrahydrocannabinol (THC) in children receiving cancer chemotherapy were compared with those of metoclopramide syrup and prochlorperazine tablets in two double-blind studies. THC was found to be a significantly better antinausea and antivomiting agent, but not all patients obtained relief of nausea and vomiting with THC. In some patients, THC enhanced appetite during a course of chemotherapy. In two patients, a "high" associated with THC administrationwas reported. Drowsiness was reported significantly more frequently with THC.