Primary papillary serous carcinoma of the peritoneum is an uncommon primary malignancy of the peritoneum and is histologically indistinguishable from papillary serous carcinoma of the ovary. The diagnosis of primary peritoneal papillary serous carcinoma should be considered in the presence of peritoneal and omental masses in the absence of an ovarian mass. Although it has been extensively documented in the pathological and gynaecological oncology literature, the CT appearance of primary papillary serous carcinoma of the peritoneum has been reported in only 51 cases in five reports. We present four patients with CT findings of pathologically proven primary papillary serous carcinoma of the peritoneum. There were a total of 23 patients with a histopathologically proven diagnosis of primary papillary serous carcinoma of the peritoneum between 1980 and 2002 with CT imaging. However, only four of the 23 patients' CT films were retrieved for retrospective evaluation. The rest of the films were not available as either patients had misplaced the films or patients were deceased.