When no visible tumor is identified at second-look laparotomy, selected biopsy specimens or cytologic washings may reveal microscopic tumor or benign pathologic atypia. The pathology material from 311 patients with epithelial ovarian carcinoma who had no macroscopic tumor at second-look laparotomy was evaluated for psammoma bodies, müllerian inclusions (benign glandular inclusions), microscopic tumor, and either inflammation or fibrosis. Progression-free intervals and survival rates were influenced by the presence of müllerian inclusions (favorably), tumor or positive cytology (unfavorably), and inflammation or fibrosis (unfavorably). Multivariate analysis (proportional hazards model) demonstrated that both the progression-free interval and survival rates were influenced significantly by the presence of microscopic tumor and tumor grade. Of 51 patients with müllerian inclusions and no microscopic tumor, 23 received additional treatment after second-look laparotomy. No differences were noted in the progression-free interval or survival rates when these patients were compared with the 28 nontreated patients. Of the treated patients, three died from chemotherapy toxicity, whereas there were no chemotherapy-related deaths in the nontreated group. These findings indicate that the presence of müllerian inclusions at second-look laparotomy does not justify treatment, and that further treatment after misinterpretation of these benign pathologic entities may lead to harmful results.