Between Sept., 1969, and Dec., 1978, 290 patients received 325 cadaveric renal allografts; 11 others transplanted elsewhere were also observed. Cancers developed in 28 patients (9.3%); 26 of these (93%) had skin cancers. The incidence of skin cancer increased by 5% annually after the 1st yr of graft function, to a cumulative 44% in those surviving 9 yr with functioning grafts. This represents an incidence of 4356/100,000 person years of post-transplant risk.sbd.20.6 times the annual incidence of skin cancer in the general population of Southern Queensland [Austalia]. Half of the patients had multiple tumors when the skin cancer was first diagnosed, after a mean latent interval of 34 mo. A total of 138 skin cancers occurred in 26 patients (average, 5.3 per patient), with a maximum of 19 in 1 individual. The ratio of basal to squamous cell carcinoma was reversed from 4:1 in the general population to 1:1.7. Conventional surgical excision gave satisfactory results, with the 1 local recurrence being controlled by reexcision. Two patients (7%) died of melanoma and metastatic squamous cell carcinoma, respectively, whereas 2 of the other 4 patients who died from cancer had coincidental skin cancer. The 2 skin cancer deaths represent only 2% of all deaths in allograft recipients. These results suggest that the problem of skin cancer in these patients can be controlled and thus is not a significant contraindication to the continued clinical use of cadaveric renal transplantation.