Study Objective: Because the ability of gastrointestinal decontamination to alter drug absorption varies inversely with time, we compared the time from arrival in the emergency department to gastrointestinal decontamination (gastric lavage or activated charcoal) for patients transported by ambulance with patients transported by other means after overdose. Methods: A retrospective chart review was conducted in an academic university ED with an annual volume of 56,000 visits. Consecutive cases of oral overdose treated by gastrointestinal decontamination between December 1, 1995, and May 31, 1996, were identified from International Classification of Diseases, ninth revision, billing codes. ED charts were reviewed to determine the patient’s age, sex, mode of transportation, disposition, and time interval to gastrointestinal decontamination with either gastric lavage or activated charcoal. Results: Two hundred eighty-one patient visits were identified. Complete data were available for 173 visits. Six patients were excluded because the diagnosis of overdose was not made on presentation, leaving 167 cases for analysis. The median age for all patients was 27 years; 95 (57%) were female. Overdose patients were transported by ambulance in 105 (67%) cases. Admission rates were similar for patients transported by ambulance and those who arrived by other means. The median interval from arrival to any gastrointestinal decontamination (lavage or charcoal) for patients transported by ambulance was shorter than patients who arrived by other means at 55 and 73 minutes, respectively (95% confidence interval for difference 2.5 to 30.5 minutes, P =.03). Subgroup analysis showed this difference was largely the result of gastric lavage. Conclusion: Overdose patients transported by ambulance have a shorter time interval from ED arrival to gastrointestinal decontamination than patients arriving by other means. This difference was largely related to more rapid gastric lavage. [Wolsey BA, McKinney PE. Does transportation by ambulance decrease time to gastrointestional decomtamination after overdose? Ann Emerg Med. June 2000;35:579-584.]