We studied 20 gastric adenocarcinoma to determine DNA ploidy pattern by flow cytometry and nucleolar organizer regions by the colloidal silver method. There were 12 diffuse and 8 intestinal type lesions. 11 tumors were classified as diploid and 9 as aneuploid. No correlation was observed between DNA ploidy pattern and mean number of nucleolar organizer regions. The histologic type was significantly related to the number of nucleolar organizer regions (p < 0.01). Poorly differentiated lesions had significantly less nucleolar organizer regions than intestinal type lesions. Lesions with ring cells (n = 6) had similar number of nucleolar organizer regions than poorly differentiated lesions.