An 82 years old man with four large tumors on his left forearm visited our hospital in July 1991. At first these tumors were suspected to be malignant. Xray, bone-scintigram and angiogram of the forearm suggested malignant tumors. There was no evidence of tuberculosis on the chest Xray when first taken. Six months later the tumor developed, producing a fistula and the patient decided to be admitted for surgery. A diagnosis of tuberculosis was made and administration of INH RFP EB was effective. It is important to be aware that tuberculosis sometimes closely resembles malignant tumors. Therefore, if a malignant tumor is suspected biopsy is necessary to make a diagnosis, keeping tuberculosis in mind.