In a population of 61 surgical patients, 10 and 15 mg dezocine were compared with meperidine 100 mg for relief of postoperative pain. Pain relief experienced by the patient and pain intensity evaluated by a nurse and a physician displayed similar characteristics: dezocine 10 mg was less effective than meperidine but dezocine 15 mg showed a rapid onset of analgesic effect with a longlasting analgesia superior to meperidine. Vital signs remained stable within satisfactory limits with no respiratory depression occurring. Blood-gas analysis showed a significant but comparable increase in PaCO2 with slight decrease of PaO2 in all patients treated with dezocine or meperidine. Side effects observed included an overt sedative effect of both analgesics, which for dezocine appeared to be dose-related.