Gingival hyperplasia is a frequent complication in transplant patients who receive cyclosporine or calcium channel blockers. We studied an unusual case involving a renal transplant recipient with post-transplant non-Hodgkin's lymphoma that manifested as gingival hyperplasia. We initially consider that it was a side effect of cyclosporine and nifedipine. The lesion did not respond to dose reductions or the withdrawal of cyclosporine and nifedipine, and the gingival hyperplasia progressed in a localized fashion, becoming ulcerated and bleeding easily. Histological examination revealed the presence of malignant lymphoma.