Background: Due to a lack of simple, inexpensive, and real-time methodology, the state of erythrocyte adhesiveness/aggregation is not measured in daily practice by most clinicians. Methods: We measured the state of erythrocyte adhesiveness/aggregation before and following the administration of intravenous high-dose gamma globulins in 18 patients with various autoimmune diseases using a simple slide test and image analysis system (INFLAMET). Results: A significant (P=0.01) increment in the state of erythrocyte adhesiveness/aggregation (from 2+/-3 to 8+/-9 arbitrary units) was noted in the entire study group despite a significant (P=0.008) decrement (from 350+/-97 to 323+/-127 mg%) in the concentration of fibrinogen and no significant change in the erythrocyte sedimentation rate (32+/-30 mm/h before and 35+/-29 mm/h following administration of gamma globulin). Conclusions: By using a simple slide test and image analysis, we were able to provide relevant rheological information that was not available from either of the routine indirect tests, i.e. the Westergren erythrocyte sedimentation rate and the concentration of fibrinogen.