Study Objective: To describe the clinical characteristics and course of γ-hydroxybutyrate (GHB) overdose. Methods: We assembled a retrospective series of all cases of GHB ingestion seen in an urban public-hospital emergency department and entered in a computerized database January 1993 through December 1996. From these cases we extracted demographic information, concurrent drug use, vital signs, Glasgow Coma Scale (GCS) score, laboratory values, and clinical course. Results: Sixty-one (69%) of the 88 patients were male. The mean age was 28 years. Thirty-four cases (39%) involved coingestion of ethanol, and 25 (28%) involved coingestion of another drug, most commonly amphetamines. Twenty-five cases (28%) had a GCS score of 3, and 28 (33%) had scores ranging from 4 through 8. The mean time to regained consciousness from initial presentation among nonintubated patients with an initial GCS of 13 or less was 146 minutes (range, 16–389). Twenty-two patients (31%) had an initial temperature of 35°C or less. Thirty-two (36%) had asymptomatic bradycardia; in 29 of these cases, the initial GCS score was 8 or less. Ten patients (11%) presented with hypotension (systolic blood pressure≤90 mm Hg); 6 of these patients also demonstrated concurrent bradycardia. Arterial blood gases were measured in 30 patients; 21 had a Pco₂ of 45 or greater, with pH ranging from 7.24 to 7.34, consistent with mild acute respiratory acidosis. Twenty-six patients (30%) had an episode of emesis; in 22 of these cases, the initial GCS was 8 or less. Conclusion: In our study population, patients who overdosed on GHB presented with a markedly decreased level of consciousness. Coingestion of ethanol or other drugs is common, as are bradycardia, hypothermia, respiratory acidosis, and emesis. Hypotension occurs occasionally. Patients typically regain consciousness spontaneously within 5 hours of the ingestion. [Chin RL, Sporer KA, Cullison B, Dyer JE, Wu TD: Clinical course of γ-hydroxybutyrate overdose. Ann Emerg Med June 1998;31: 716-722.]