Up to 30% of patients with an organ transplantation develop precancerous lesions and malignant tumors, especially of the skin. All 241 patients who underwent heart transplantation from 1990 to 2000 were evaluated with regard to the development of neoplasias. Those alive in September 1999 were referred for a standardized dermatological exam (n=156) which detected malignancy in 28 patients being transplanted for 4.98 years on average. The skin was the organ most frequently involved (64%, n=18). 18% (n=5) of tumors were found in the urinary and genital tract, 7% (n=2) each in the respiratory and gastrointestinal tract, and 4% (n=1 ) in the breasts. The average age of patients who developed tumors was significantly higher as compared to the overall mean age (59.5+/-5 vs 49.8+/-14.7 years, p=0.00027). There was no correlation between development of malignancy and HLA matching, immunosuppressive drugs used, dosage and serum levels of immunosuppressive medication, and episodes of transplant rejection. Our study shows that the risk to develop tumors is at least doubled after heart transplantation. Due to the high incidence of skin tumors, transplant patients should undergo dermatological examinations on a regular basis.