Squamous cell carcinoma (SCC) of the eye occurs at substantially increased rates in individuals with human immunodeficiency virus (HIV) infection, but it has not been reported in individuals with iatrogenic or congenital immune deficiency. In a national, population-based cohort of 10180 renal transplantation patients from Australia with 86898 person-years of follow-up, we ascertained primary incident cancers diagnosed in 1982–2003 by record linkage between the Australia and New Zealand Dialysis and Transplant Registry and the Australian National Cancer Statistics Clearing House. Standardized incidence ratios (SIRs) of cancer were calculated using age-, sex-, calendar year–, and state/territory–specific population cancer incidence rates. Statistical tests were two-sided. Five patients were diagnosed with ocular SCC after kidney transplantation (0.26 were expected), and the incidence was increased 20-fold (SIR = 19.5, 95% confidence interval [CI] = 6.3 to 45.5). Compared with the entire cohort, the five patients with ocular SCC after transplantation were more likely to have resided in the subtropical state of Queensland (60% versus 17%, P = .04), to have had end-stage kidney disease as a result of glomerulonephritis (100% versus 46%, P = .02), and to have a history of cutaneous SCC (100% versus 29%, P = .002). The increased incidence of ocular SCC after kidney transplantation and after HIV infection strongly suggests that this neoplasm is an immune deficiency–associated cancer. Our data also support an interaction between immune suppression and sun exposure in the development of ocular SCC after kidney transplantation. ; Claire M. Vajdic, Marina T. van Leeuwen, Stephen P. McDonald, Margaret R. E. McCredie, Matthew Law, Jeremy R. Chapman, Angela C. Webster, John M. Kaldor, Andrew E. Grulich ; © The Author 2007. Published by Oxford University Press.