Of 292 adult sagebrush lizards (Sceloporus graciosus) examined for the stomach nematode, Physaloptera retusa, 81 (28%) were infected. Attached nematodes caused erosive inflammatory foci in the stomach mucosa. Early lesions were U-shaped. Degenerating gastric glands occurred in the adjacent mucosa. Healed lesions were fibrous connective tissue scars; regenerating gastric glands occurred at the periphery. There were no externally visible signs of infection.