A gastrectomy specimen containing two tubular adenomas from a 67-year-old woman was mapped by an improved method using selective histochemical staining. The specimen was divided into 83 blocks measuring 4.0 cm x 0.5 cm. Sections from the blocks were stained with alcian blue (pH 2.5) to detect mucin. Alcian blue-stained fields were easily identified and measured with the aid of a MOP 30 interactive digital image analyzer. The total area of gastric mucosa analyzed in the 83 sections measured 3,270.9 sq mm while the area occupied by alcian blue-stained goblet cells measured 755.9 sq mm (23.1% of the total area). Intestinal metaplasia was present in 46 of 83 blocks. Both the mean size of alcian blue-positive fields per section as well as the number of alcian blue-positive fields per section were significantly larger in the antral zone I and the intermediate zone II than in the fundal zones III, IV and V. The highest proportion of gastric mucosa with intestinal metaplasia was not found around the two gastric adenomas, but elsewhere. There was no significant difference in the proportion of intestinal metaplasia between the greater and lesser curvatures, further challenging the belief that intestinal metaplasia is always greatest along the lesser curvature. The method described will permit future studies of the possible association between intestinal metaplasia and dysplasias and adenocarcinomas of the stomach.