We report the first case of angiotropic large-cell lymphoma (intravascular malignant lymphomatosis) presenting as minimal change disease (MCD) and diagnosed by renal biopsy. Neoplastic lymphoid cells were disseminated throughout the glomerular capillary bed and were associated with diffuse foot process effacement. The tumor had the immunophenotype of a B cell lymphoma (reactive with LCA and L-26 and unreactive with FVIII-R-Ag, Leu-M-1, alpha-1-antichymotrypsin, lysozyme, UCHL-1, Leu-22, kappa, and lambda). The temporal association between the onset of lymphoma and MCD, and the failure of the nephrotic syndrome to respond to immunosuppressive therapy support a role for lymphoma in the pathogenesis of MCD in this patient.