Four cases showing different means to detect cryoglobulins are reported: effects on blood cell counts performed on 2 technologically different automated hematology instruments and microscopic features in fresh blood samples and on May-Grünwald-Giemsa-stained bloodfilms. These cases were chosen for their instructive value in depicting all artifacts associated with cryoglobulins. Laboratory recognition of the cryoglobulins is important to correct factitious results with automated blood cell counters, mainly pseudoleukocytosis and pseudothrombocytosis. Moreover cryoglobulin-induced laboratory artifacts may be the first factor prompting the assessment for cryoglobulinemia and the diagnosis of the underlying cause.