Analyses of cytophotometrically determined DNA content and mitotic rate were carried out in 37 cases of gastric carcinoma to identify biologic significance of DNA abnormalities. Lymph node metastasis was also evaluated by DNA content and mitotic rate. According to the linear regression analysis, there were statistically significant correlations of mitotic rate with DNA variants such as the peak value, the mean value, and the frequency of cells with values exceeding tetraploid or hexaploid chromosome complement. There were significantly higher values for these DNA parameters in patients with lymph node metastasis compared with those without metastasis. Similarly, higher mitotic rates were observed in tumors with metastatic disease. Thus abnormal DNA fractions appear to be indicative of tumors with a high mitotic activity. The quantitative detection of the DNA abnormalities will provide pertinent biologic information required to predict the occurrence of metastasis in patients with gastric cancer.