Malignant peritoneal mesothelioma (MPM) is a rare and often rapidly fatal disease with median survival of 5 to 12 months for untreated cases and 16 months reported after multimodality treatment. We report a prospective clinical treatment study using cytoreductive surgery combined with intraoperative intraperitoneal heated chemotherapy (IPHC) perfusion using mitomycin C for MPM. Twelve patients (11 male with a mean age 51 years) were treated. Seven patients presented with bulky disease and seven with ascites. All underwent exploratory laparotomy with histologically confirmed diagnosis of MPM. Surgical debulking as feasible was performed. Complete gross tumor removal was possible in only one patient. Cytoreduction was followed by a 2-hour closed low-volume IPHC using mitomycin C. One patient died 50 days postoperatively from complications relating to small bowel perforation. Hematologic toxicity of the procedure was minimal. Ascites was controlled in all patients and permanently in 86 per cent of patients presenting with ascites. To date median survival is 34.2 months with median follow-up of 45.2 months. One patient was re-explored for ventral hernia 2 years post-IPHC, had negative peritoneal biopsies, and remains disease-free at 5 years. Given the dismal prognosis associated with MPM the results of treatment with cytoreductive surgery combined with IPHC perfusion are encouraging. The rarity of MPM makes appropriately powered prospective randomized trials unlikely. Therefore, we now offer this approach off protocol; however, further study of this combined modality therapy is warranted.