Tc-pertechnetate scintigraphy was performed in 81 infants and children, clinically suspected to have Meckel's diverticulum with ectopic gastric mucosa. The predominant symptom was rectal bleeding and anemia. Twenty-two patients underwent laparotomy and 12 had Meckel's diverticulum with ectopic gastric mucosa. In operated patients the sensitivity of scintigraphy in detecting ectopic gastric mucosa was 0.75, the specificity 1.0 and the diagnostic accuracy 0.86; the diagnostic accuracy was estimated to 0.96 for the whole material. Histologic examination of the diverticula showed a smaller area of the ectopic mucosa in cases with negative scintigraphic findings. In addition, prominent fibrosis seemed to be a more consistent finding in cases with negative as opposed to those with positive scintigraphic findings. Presence of anemia may provide a guideline as to whether or not scintigraphy is indicated.