A 75-year-old man with a 2-year history of end-stage renal disease had skin lesions on both feet (A) for 2 weeks. The cause of end-stage renal disease remained to be clarified. Initial laboratory tests showed the following values: Hb level, 4.6 g/dL; leukocyte count, 4.6×10⁹/L; and platelet count, 483×10⁹/L. Peripheral blood (PB) smear showed extracellular aggregates of pink-tan acellular material (B). We suspected cryoglobulinemia and performed the cryoglobulin test. The sampling was performed using a warmed syringe and a test tube. The patient was positive with a very high cryocrit level (37.02%). Immunofixation showed a monoclonal IgG kappa band in the gamma region. The patient was negative for hepatitis and HIV. Biopsy of the skin lesion showed leukocytoclastic vasculitis with subcorneal bulla. A subsequent bone marrow (BM) examination showed no evidence of clonal plasma cells (<2%). Flow cytometric analyses showed increased proportion of B cells (PB, 24.4&; BM aspirates, 25.5%) with no clonality. Cytogenetic study revealed normal karyotype of 46,XY. The patient was diagnosed with type I cryoglobulinemia with cryoglobulinemic vasculitis and monoclonal gammopathy. Treatment with methyl prednisolone improved his clinical response. Our data indicate that cryoglobulin could be easily detected by PB smear.