Immunohistochemistry and RT-qPCR were applied to detect the expression of SMO and GLI1 proteins and mRNA in biopsy specimens and plasma cavity effusion specimens from malignant mesothelioma (n = 130) and benign mesothelial tissues (n = 50) and to analyze the clinicopathological significance and survival risk factors of SMO and GLI1 protein expression in mesothelioma. The gene discussed is SMO; the disease is malignant mesothelioma.