REASON FOR PERFORMING STUDY: Diagnostic techniques for oviductal obstruction in the mare are limited and development of a more reliable and direct method to assess oviductal patency is needed. OBJECTIVE: To evaluate the feasibility of hysteroscopic selective hydrotubation of the equine oviduct via videoendoscopy in standing mares. METHODS: Using a catheter inserted under endoscopic guidance into the uterotubal junctions of 10 mares, 5 ml of indigo carmine solution (4 mg/ml) was flushed into the oviduct. After introduction of the dye, peritoneal fluid was obtained via abdominocentesis. A colpotomy was also performed to allow introduction of a videoendoscope into the abdominal cavity to assess the presence of dye visually at the ovarian end of the oviduct. RESULTS AND CONCLUSIONS: In 15 of 20 (75.0%) attempts, the catheter was successfully inserted into the uterotubal junction, and dye was observed at the ampulla, fimbria, overlying the ovary or surrounding tissue. In 2 mares, the videoendoscope could not be manipulated to identify the uterotubal junction. Only one of 2 oviducts was flushed in an additional mare because insufflation of the uterus could not be maintained. The colour of the dye was evident macroscopically and spectrophotometrically in 4 of 8 mares from which peritoneal fluid was successfully collected. POTENTIAL RELEVANCE: The equine oviduct can be evaluated by hysteroscopic selective hydrotubation.