Despite widespread use of a parenterally administered mixture of meperidine, promethazine, and chlorpromazine (Demerol, Phenergan, and Thorazine, DPT), there has been no systematic evaluation of its efficacy and complications in emergency department patients. We reviewed the medical records of all patients less than 16 years old who received DPT in our ED during the 24-month period ending December 31, 1987. Of 487 patients who received DPT, the maximum dose was 50/25/25 mg, respectively. Wound repair (69%) and fracture reduction (12%) were the two most common indications. Lacerations most commonly involved the face (65%) or digits (20%). Efficacy was not directly reported, but only eight patients received repeat sedation. Head injuries and a lower mean initial meperidine dosage were more prevalent in patients requiring repeat sedation (P less than .05). Three patients (0.6%) experienced significant complications. All had respiratory depression and received IV naloxone. An abnormal initial mental status examination or an underlying neurologic abnormality was significantly associated with complications (P less than .05). DPT appears to be a safe and relatively effective sedative for selected pediatric ED patients when administered as a ratio of 2:1:1 mg/kg, respectively. Complications are increased in patients with acute or underlying neurologic abnormalities.