Australia is currently experiencing an epidemic of malignant mesothelioma. The clinical aspects of malignant mesothelioma were investigated in 295 Australian patients as part of a national study of the disease. Most patients were male (91%), with the mean age at diagnosis being 64 years. The predominant cell type was epithelial (38%) and the majority of primary tumours arose from the pleura (94%). Mean survival was poor (17.6 months from first symptom; 11.8 months from diagnosis). Patients with a pleural primary tumour were more likely to present with dyspnoea, chest pain and cough; to have a pleural effusion diagnosed radiologically; and to have metastatic spread. Patients with a peritoneal primary tumour were more likely to present with weight loss, loss of appetite, abdominal pain and ascites; to have radiologic evidence of asbestos exposure; and to have spread along a needle track created during a diagnostic tap. A minority of patients had past thoracic conditions, or radiologic findings, specifically related to previous asbestos exposure. About one fifth of patients had no known asbestos exposure. Forty-one per cent of subjects received some form of chemotherapy, radiotherapy and/or surgery, but no formal disease staging had been documented for any patient. Proper controlled trials of secondary and tertiary treatments in malignant mesothelioma are now needed.