We report a case of chronic active Epstein-Barr (EB) virus infection (CAEBV) associated with skin eruptions mimicking hydroa vacciniforme (HV) in a 4-year-old boy. The patient had repeated episodes of vesiculo-necrotic eruptions on the face, scalp, and bilateral forearms one year before the first visit to our department. General symptoms including fever, hepatosplenomegaly, abnormal liver function, and cervical lymph node swelling were noted three months before the first visit. At the first visit, small, bean-sized, erythemic papules with central necrosis were observed on the face and anterior chest wall. Thumb-sized ulcers with crust were present on the bilateral forearms. Histopathological examination of an erythematous lesion in the submandibular area revealed parakeratosis with a thick crust, mild spongiosis in the epidermis, and a dense infiltration of lymphoid cells into the dermis and perivascular space. Laboratory examination showed EBNA x 40, EBV VCA IgG x 1,280, and EBV DNA (PCR) 8 x 10(4). EBV-encoded small nuclear RNA (EBER) positive cells were detected in the dermis by an in situ hybridization (ISH) method. Large granular lymphocytes (65%) with the NK cell phenotype were found in the peripheral blood. A real time PCR method showed 171,741 copies/ micro g DNA in CD 16 positive cells. Although latent EBV infection-associated eruptions have been documented, detailed skin manifestations in CAEBV are less well known.