A patient with essential mixed cryoglobulinemia was treated for deteriorating renal function with plasma exchange alone. This therapy was immediately followed by acute oliguric renal failure due to precipitation of the cryoglobulin within glomerular capillary loops, probably as a result of infusion of cold plasma. The composition of the intracapillary deposits reflected not only the variety of cryoglobulin but the rapidity of deposition. Renal function returned when plasma exchange was re-introduced, this time coupled with immunosuppressive chemotherapy. After resolution of the intraluminal caogula a membranoproliferative picture remained. Replacement fluids for plasma exchange in cryoglobulinemia should be warmed before infusion.