Objective - To determine if intravenous lidocaine is useful and safe as a treatment for equine ileus. Study Design - Prospective double-blinded placebo-controlled trial. Study Population - Horses (n=32) with a diagnosis of postoperative ileus (POI) or enteritis and that had refluxed >20 L or had been refluxing for >24 hours. Methods - Refluxing horses were administered lidocaine (1.3 mg/kg intravenously [IV] as a bolus followed by a 0.05 mg/kg/min infusion) or saline (0.9% NaCl) solution placebo for 24 hours. Variables evaluated included volume and duration of reflux, time to 1st fecal passage, signs of pain, analgesic use, heart rate and arrhythmias, respiratory rate, temperature, days of hospitalization, outcome (survival to discharge), and complications. Results - Of the lidocaine-treated horses, 65% (11/17) stopped refluxing within 30 hours (mean±SD, 15.2±2.4 hours) whereas 27% (4/15) of the saline-treated horses stopped within 30 hours. Fecal passage was significantly correlated with response to treatment; horses that responded to lidocaine passed feces within 16 hours of starting the infusion. Compared with placebo treatment, lidocaine treatment resulted in shorter hospitalization time for survivors, equivalent survival to discharge, no clinically significant changes in physical or laboratory variables, and no difference in the rate of incisional infections, jugular thrombosis, laminitis, or diarrhea. Muscle fasciculations occurred in 3 lidocaine-treated horses (18%). Conclusion - IV lidocaine significantly improved the clinical course in refluxing horses with minimal side effects. Clinical Relevance - At the infusion rate studied, IV lidocaine is safe and should be considered for the treatment of equine ileus.