Over a period of three years (1989-1992) five children suffering from localized scleroderma were seen at the Department of Pediatrics of the University of Trieste. Evidence of a previous infectious mononucleosis (IM) was present in four out of five patients. The clinical history of these four children is reported. The association between the appearance of scleroderma and a previous viral infection is not surprising. However, in the pediatric literature there is only one case of progressive systemic sclerosis (PSS) developing in a 15-month-old girl less than one month after she contracted IM. The presence of shared epitopes between an Epstein-Barr virus protein, BOLF1, and the hypervariable region of HLA associated with the pauciarticular form of JCA, recently reported, could provide a key to the pathogenesis of other collagen diseases such as scleroderma.