Physaloptera brevivaginata has been found parasitising the stomach of two species of bats of the family Vesperti-lionidae, Myotis myotis and Myotis blythii, in Spain. A comparative study of the prevalences and mean intensities of parasitism by this physalopterid revealed no statistically significant differences between the two hosts. Likewise, no relationship was found between parasite intensity and host body weight. The histopathological study of the stomach lesion revealed destruction of the mucosa, with degeneration of the gastric glands, loss of the muscularis mucosae and focal necrosis at the points where the cephalic extremities of both sexes of this nematode attach to the mucosa. The present paper is the first study of gastric pathology caused by an adult physalopterid in bats.