OBJECTIVE: The aim of this retrospective analysis was to study the incidence, clinical course, treatment, prognosis of malignancy in immunosuppressed renal transplant recipients. METHODS: The object were 38 cases of cancer that occured in 1,130 transplant recipients between 1969 and 1997 at Kangnam CUMC. Mean follow-up periods was 61.6+/-41.8 months. The incidence of cancers was compared to the number expected in age-matched general population. This allows the calculation of a "risk ratio". We used international cancer registry for comparison. RESULTS: Thes incidence of de novo malignancy in 1,130 renal transplant recipients was 3.3% for 5years of mean follow-up period and there was no difference between sex. The most common cancer was stomach cancer in case of male and cervix cancer for female. This distribution was same as general population. The incidence of malignant lymphoma and Kaposi's sarcoma was higher in renal transplanted patients than the general population. Cancers with the most striking increased risk(IR) were lymphoma(IR 167), and Kaposis sarcoma. It took 55 months for the malignant lymphoma to be occurred and it developed faster than other cancer. CsA caused faster breakout of cancer than Aza did. CONCLUSION: The features of malignancy in renal transplant recipients are different from those of general population.