Pathogenicity of parvovirus B19 has been demonstrated. The spectrum of clinical manifestations varies according to the age and immune status of affected patients. Parvovirus B19 is the aetiologic agent of erythema infectiosum in children. In normal adults, it is responsible for acute, bilateral and symmetrical arthritis, although chronic arthritis can develop. Parvovirus B19 has a particular tropism for erythroid precursors: in patients with underlying hemolysis, it induces transient aplastic crisis; in immunosuppressed patients the virus can lead to chronic pure red cell aplasia. Hydrops fetalis is one of the most severe manifestation of the infection. Diagnosis of recent parvovirus B19 infection is based upon serology and PCR, especially in immunosuppressed patients in whom polyvalent intravenous immunoglobulins must be started. The link between parvovirus B19 and systemic vasculitis is questioned.