AIM: Peritoneal mesothelioma (PM) has rarely been studied. The Expanded Access Program (EAP) provided access to 109 patients with PM. METHODS: This was a nonrandomized, open-label study conducted in chemo-naïve or previously treated patients with PM not amenable to curative surgery. Patients received pemetrexed (PEM) 500 mg/m2 alone or with cisplatin (CIS) 75 mg/m2 or carboplatin (CARBO) AUC 5 every 21 days, supplemented with standard vitamin B(12), folate, and dexamethasone. RESULTS: Response rates (95% CI) for PEM, PEM/CIS, and PEM/CARBO were 12.5% (3.5, 29.0), 20.0% (7.7, 38.6), and 24.1% (10.3, 43.5), respectively. Median survival for PEM was 10.3 months. One-year survival rates for PEM/CIS and PEM were 57.4% (95% CI: 10.3, 100) and 41.5% (95% CI: 4.6, 78.4), respectively, and were not available for PEM/CARBO. Anemia was the most common serious adverse event (6.4%). Neutropenia (34.6%) was the most frequent CTC grade 3 or 4 toxicity reported. CONCLUDING STATEMENT: PEM with or without a platinum agent was both active and well tolerated in patients with peritoneal mesothelioma.