Parvovirus-B19 (PV-B19) is a member of Parvoviridae, which is one of the smallest DNA viruses. PV-B19-associated diseases usually serve as a good representation of the balance of virus, host response and the immune system. The diseases manifested with PV-B19 are erythema infectiosum, which is common in children, hydrops fetalis, transient pure red cell aplasia in patients with chronic hemolytic anemia, arthralgia -mostly observed in women, and chronic pure red cell aplasia in immunocompromised individuals. Cytopenia (bicytopenia, monocytopenia or pancytopenia) may also accompany the diseases mentioned above. On the other hand, there are many diseases, including neurologic, vasculitic, hepatic, rheumatoid, nephritic, autoimmune, myocardial, and others in which the mechanisms of the diseases are not clear, which may be associated with PV-B19. The virus may manifest with unexpected and unexplained clinical pictures and lead to misdiagnosis. Therefore, hematologic disorders in any unestablished clinical diagnosis should be investigated for PV-B19 infection. However, serologic examination for PV-B19 diagnosis is not sufficient in immunocompromised status. The virus can be determined with polymerase chain reaction (PCR) in the serum or tissue samples. Supportive therapy, blood transfusion and immunoglobulin are the conventional therapeutic interventions for PV-B19 today. Vaccination studies are under examination. (Turk J Hematol 2010; 27: 224-33) Key words: Children, hematologic findings, parvovirus, treatment