Between January 1, 1970, and December 31, 1983, 817 patients with serous ovarian carcinoma were seen at M. D. Anderson Cancer Center. Within this population, we identified those patients with normal-sized ovaries (4 cm or less in maximum diameter) and those with papillary serous histology, exclusive of borderline tumors. The 74 patients so identified were classified as having papillary serous carcinoma of the peritoneum, and form the basis of this report. The average age at diagnosis was 57.4 years. The majority of the patients (90.5%) were white. Common presenting symptoms included abdominal pain (54.9%) and abdominal distention (51.5%). In 89.1% of patients, disease involved the omentum. Clinical response to chemotherapy was seen in 63.6% of the patients; 40.9% of them had partial responses and 22.7% complete responses. At second-look laparotomy, 27.3% of 33 patients demonstrated a surgical complete response, 21.2% had microscopically positive disease only, and 51.1% had grossly positive disease. The median survival for the total group was 24.0 months. Neither patient age nor presence of residual disease after cytoreduction predicted survival. Patients treated with combination chemotherapy fared better than patients treated with single-agent regimens (29.5 versus 16.5 months; P = .01). Patients receiving cisplatin-containing regimens also did better (31.5 versus 19.5 months; P = .02). Among several pathologic characteristics analyzed, only the absence of mitoses predicted improved survival (76.5 versus 21.4-27.0 months; P less than or equal to .05). Papillary serous carcinoma of the peritoneum, though biologically and histologically similar to ovarian carcinoma, is a distinct clinicopathologic entity not uncommonly encountered by the gynecologist.