6 cases of acrodermatitis papulosa eruptiva infantum (acrodermatitis papulosa infantilis or Gianotti-Crostisyndrome: G.C.S.) were observed and the clinical features of this disease are discussed. 1. An erythemato-papular dermatitis mainly of the face, legs, arms, buttocks, not itching, without re-occurrence lasting on the average 20--25 days. 2. An distinct enlargement of the lymph nodes, especially of the inguinal and axillary areas (reactive reticulo-histocytic lymphadenitis). 3. Acute hepatitis, mostly without icterus. 4. Presence of HB Ag-Australia Antigen in the serum of patients a few days after the onset of the disease. Doubts concerning the entity of G.C.S. are getting irrelevant considering the distinct characteristics. The viral genesis already suggested by Gianotti and Crosti of the picture of the disease seems to be true: in all cases Australian antigens are positive. The infectiousness, but the small danger of infection, even if the disease dates back a few months, should not be underestimated. When diagnosing G.C.S. among others the akrolocalized papular-vesicular syndrome described by Crosti and Gianotti should be considered. In 2 patients we could find by electron microscopic studies microtubular aggregates having a diameter of 200 A. These aggregates were situated in the cytoplasm of endothelial cells of smaller vessels in the upper part of the corium.