Cryoglobulins are proteins that precipitate spontaneously and reversibly at less than body temperature within 3 days. They are insoluble at 4°C and may aggregate upto 30°C. They have a tendency to fix complement and initiate inflammatory reaction. This assay is useful for evaluating patients with Vasculitis, Glomerulonephritis and Lymphoproliferative disease. It also helps to evaluate patients with Macroglobulinemia and Myeloma who are symptomatic on exposure to cold.