- Numerous germline mutations in the adenomatous polyposis coli (APC) tumor-suppressor gene are responsible for development of multiple adenomatous colorectal polyps with their inevitable progression to cancer. Multiple attempts at dietary and pharmacological prevention of colorectal carcinoma development in patients with familial adenomatous polyposis (FAP) have provided conflicting results. Immunosuppressive treatment with tacrolimus is known to be associated with an increased risk of malignancy and should be avoided in patients with high propensity for development of neoplasia. We observed a complete reversion of FAP phenotype in a male teenager carrying a germline mutation in APC gene who underwent a kidney transplant due to end-stage kidney disease secondary to congenital dysplastic kidneys. The patient was treated with tacrolimus and mycophenolate mofetil after transplantation. The possible chemopreventative role of these agents should be evaluated and confirmed in a larger cohort. The elucidation of molecular mechanisms underpinning the observed chemopreventative effect of tacrolimus and mycophenolate mofetil might lead to the development of a novel colorectal cancer therapy.