A retrospective analysis of 143 studies of abdominal scintigraphy with technetium-99m pertechnetate for the diagnosis of ectopic gastric mucosa (usually located in Meckel diverticulum) was undertaken. The rectilinear scanner was used for 57 studies and the gamma camera for 86. The final diagnosis, at laparotomy or after clinical and laboratory investigation with long-term clinical follow-up, was correlated to the interpretation of the scintigrams. Of 57 rectilinear scans, five were true positive, 46 true negative, two false positive, and four false negative. Of the 86 camera studies 10 were true positive, 74 true negative, one false negative, and one patient showed large bowel activity (positive atypical study). The results of this analysis indicate the value of the properly performed and interpreted abdominal pertechnetate scintigraphy in the diagnosis of (bleeding) ectopic gastric mucosa; it was also shown that the sensitivity and the specificity of this test have improved since the introduction of the gamma camera and the standardization of the procedure.