Cancer is a well-recognized complication of kidney transplantation (KT), but nearly almost all data have come from Western countries. The aim of this study was to determine the incidence, type, and risk factors of malignancy after KT in Korea. The 1695 patients who underwent KT between 1969 and 2009 were studied retrospectively. Results were compared with a cohort of patients without cancer from the same center. During the follow-up period, 136 of 1695 patients developed 141 post-transplant malignancies (PTM). The cumulative incidence of cancer at 1, 5, 10, 20, and 30 years was 0.64%, 2.42%, 7.89%, 21.49%, and 66.35% respectively. Stomach cancer was the most common PTM. Risk of Kaposi sarcoma, malignant lymphoma, skin cancer, cervical cancer, and renal cell carcinoma was more than 10-times higher in KT recipients. Multivariate logistic regression analysis showed that cancers were clearly associated with recipients’ age, recipients’ gender, duration of graft function and follow-up period. Our data suggest that most malignancies develop more frequently after KT, but the incidence of individual cancer is different from Western countries. A more vigorous cancer surveillance program should be adapted to risk associated with transplant recipients, especially older, female or long-term follow-up recipients or those with functioning grafts.