Kaposi's sarcoma (KS) is one of the most common post transplant malignancies. A variety of factors appears to contribute to the development of KS including genetic factors, sex hormones, immunosuppression and oncogene viruses. We present 3 cases with concurrent KS and cytomegalovirus (CMV) infection in the first year after kidney transplantation. The suspicion on KS due to the skin lesions was confirmed by biopsy. The diagnosis of CMV infection was made by detecting pp65 antigen in blood. The KS lesions were limited to the skin in 2 patients, while skin and gastrointestinal tract were involved in 1 patient. Many factors are reported to be involved in KS development, but the simultaneous occurrence of KS and CMV infection in our three cases suggested CMV as an inducing factor for KS.