Kaposi's sarcoma (KS) is one of the most common tumors to occur in kidney recipients, especially in Middle Eastern countries. KS limited to penis has rarely been reported and is usually observed in patients with AIDS. Herein, we describe a 35-year-old HIV-negative man who had undergone kidney transplantation one year earlier and subsequently had presented with an isolated KS on the penis associated with concurrent infection by cytomegalovirus (CMV). KS was successfully cured by withdrawing immunosuppressive agents, chemotherapy and radiotherapy. His renal allograft function remained stable during 3 years of follow up. To our knowledge, this case is the first report of penile KS associated with CMV infection, and early diagnosis and prompt treatment of a rare complication of a common disease such as KS is essential.