We studied effects of changed blood theology in cryoglobulinemia on temperature-dependent disorders of peripheral circulation. The rheological status was assessed by aggregation characteristics of blood at temperature 37 degrees C and 4 degrees C at nephelometry of reverse light diffusion. Blood cryoglobulins concentration was determined spectrophotometrically. Turbidimetry estimated the size of cryocomplexes at different temperatures and energetic characteristics of their formation. It was found that blood of healthy donors in cooling does not change its rheological properties significantly. Blood of patients with cryoglobulinemia cooled to 4 degrees accelerated formation of linear erythrocyte aggregates and increased their strength. The results agreed with estimated values of molecular connection energy in cryocomplexes. The greatest difference between the patients' and donors' blood was in strength of the largest aggregates. Sharp strengthening of both large and small aggregates in blood cooling makes vascular red cell desaggregation impossible. This may entail microcirculatory arrest.