Herpes Zoster disease is one of the most difficult skin diseases to treat and everyone can experience it, the characteristic of this disease is marked by unilateral vesicular grouped with pain marked with radicular around the dermatome. This study aims to build bayes theorem method using Visual Basic 2008 as a tool to diagnose skin diseases. With this application does not have to wait long to anticipate treatment quickly and precisely. How to use this application is the admin input questions in the form of symptoms experienced by the patient, then the system will process all the patient answers using Bayes method a nd the system will output the results of the diagnosis of the type of disease. The built system can help the patient in knowing the type of illness that is being suffered by the patient and in accordance with the expert analysis of skin diseases.