INTRODUCTION News organizations and governmental agencies have reported substantial increases in the number of opioid-related overdose cases in recent years. OBJECTIVE To describe the utilization of emergency medical services (EMS) for suspected opioid-related overdose cases in a rural state during the period 1997 through 2002. METHODS Statewide EMS records were reviewed for 1997 through 2002. Data reviewed included prehospital diagnosis and medications given to all patients by prehospital providers. For cases with a prehospital diagnosis of poisoning or overdose, data reviewed included medications given to patients by prehospital providers, pupil size, and respiratory rate. All records were reviewed in a defined sequence. RESULTS The study period encompassed 1,175,781 patient encounters. Poisoning or overdose patients accounted for 19,808 (1.7%) encounters. Naloxone was administered by the EMS provider to 2,668 (0.2%) patients. For all poisoning or overdose patients, 1,308 (6.6%) had miotic pupils, 450 (2.2%) had a respiratory rate of <12 breaths/min, and 1,569 (7.9%) received naloxone. During the investigation period, total EMS patient encounters increased 25%, while patients with a complaint of poisoning or overdose increased 47%. The incidences of EMS overdose patients with miotic pupils, respiratory rate <10 breaths/min, and naloxone administration increased 167%, 295%, and 154%, respectively. CONCLUSION In this rural state, prehospital patients with findings suspicious for opioid overdose disproportionately outpaced the growth of all EMS encounters as well as general overdose encounters during the defined investigation period.