The recovery of cannabinoids was investigated by combustion of marihuana cigarettes in a specially constructed smoking machine, with air flow parameters varying within potential human physiological limits. Combustion temperature was found to be about 600°. Percentage recovery of tetrahydrocannabinol in the smoke increased slightly but significantly with increasing air flow rate, but was unaffected by continuous versus intermittent flow. Maximum recovery after complete combustion was about 60%, with negligible change in cannabinoid ratios. Synthetic tetrahydrocannabinol applied to tobacco or alfalfa cigarettes was less completely recovered. Total dry residue (tar content) of the cannabis smoke was somewhat greater than that of tobacco smoke.