AbstractBackground.A retrospective study was performed on 51 patients with adenoid cystic carcinomas to see whether DNA ploidy, tumor stage, and histopathologic grading correlated with prognosis.Methods.Histopathologic grading was performed according to Szanto et al and DNA content was estimated from archived material using the technique by Hedley et al.Results.Thirty‐nine tumors were DNA diploid and 12 were DNA aneuploid. Histologic grade III was more often associated with DNA aneuploidy than the lower grades (p= 0.011). DNA ploidy also correlated with clinical stage (p= 0.011). Log‐rank analysis and Cox regression analysis of treatment failures revealed significant findings for S‐phase value and DNA ploidy.Conclusions.Our results indicate that DNA ploidy estimations, S‐phase value, and histologic grading are prognostic factors in adenoid cystic carcinomas. These examinations should therefore be incorporated in the evaluation of patients with adenoid cystic carcinomas. © 1995 Jons Wiley&S