To study the correlation between flow cytometrically measured DNA ploidy with prognostically important histopathologic groups and clinical outcome in patients with adenoid cystic carcinoma of the salivary glands. 46 tumor specimens were analyzed flow cytometrically for DNA content and assessed for histological grade. Correlations were made between tumor DNA ploidy and histopathological grade, and disease-free and overall survival of these patients. Of the 46 patients, 31 had a cribiform/tubular histologic pattern, and 15 had a solid pattern. 84% of the tumors with cribriform/tubular pattern were DNA diploid, compared with 33% of tumors that were graded solid. This difference proved to be statistically significant (chi(2)11.75, P = 0.0006). Overall and disease-free survival periods were longer for patients with DNA diploid tumors in both groups, 63% vs. 36% and 62% vs 38%, respectively. Tumor DNA ploidy correlates with prognostically important tumor histopathology as well as overall and disease-free survival in patients with adenoid cystic carcinoma of the salivary gland. B-3.