OBJECTIVE To study nuclear DNA content and morphological parameters in ovarian cystadenocarcinoma. METHODS Nuclear DNA content and morphological parameters were quantitatively determined by image analysis technology in 56 cases of ovarian cystadenocarcinoma, 12 benign ovarian cystadenoma and 10 normal ovarian epithelial tissue. RESULTS DNA content of ovarian cystadenocarcinoma was the highest among the three groups; and there were significant differences between the groups (P < 0.01). In the aspect of morphometry, nuclear circle was greatly different among the three groups (P < 0.01). There was no significant variances in nuclear parameter and area (P > 0.05). Nuclear DNA content of ovarian cystadenocarcinoma was related to its histopathological classification, histological grade and clinical stages (P < 0.01, P < 0.05). There was a reverse relationship between the DNA ploidy level and clinical prognosis. The 2-year survival rate of ovarian cystadenocarcinoma with diploidy/near diploidy pattern was higher than that with aneuploid pattern (P < 0.01). CONCLUSIONS Nuclear DNA content of ovarian cystadenocarcinoma is a useful marker in reflecting the biological behavior and is of practical value in diagnosis, the choice of treatment methods and in the evaluation of results and prognosis.