Background: Overexpression of cyclin D1 and p53 protein has been reported in many types of malignant tumors. Objectives: We investigated whether cyclin D1 was detected immunohistochemically in various types of malignant tumors of the skin, comparable with p53 protein. Methods: Immunohistochemical staining of cyclin D1 and p53 protein was applied to squamous cell carcinoma, malignant melanoma and malignant fibrous histiocytoma and various kinds of benign skin tumors. Results: Cyclin D1 was positive only in malignant tumors at the same incidence as p53 protein. Conclusion: Cyclin D1 immunohistochemical staining may be a malignant marker for various skin tumors.