Infection with the stomach worm Physaloptera spp. in dogs can cause chronic vomiting, although the diagnosis is often difficult owing to a low worm burden, single-sex infections, a failure to produce ova, or ova that are of greater density than solutions routinely used for qualitative fecal flotation. A retrospective evaluation was performed of 27 dogs that had gastric Physaloptera spp. infection confirmed endoscopically. In 23 of 27 dogs (85.2%), chronic vomiting was the chief complaint, and Physaloptera was an incidental finding in 3 dogs with esophageal or gastric foreign bodies. The worm burden was low (1–3 worms) in 21 dogs (77.8%), but 2 dogs were infected with large numbers (>50 worms). Prior therapy with routine doses of anthelmintics was ineffective in eight dogs prior to endoscopy. A higher dose and longer duration of fenbendazole in combination with pyrantel pamoate is recommended for treatment of suspected or confirmed infections. Reinfection is common in some dogs and should not be viewed as treatment failure.