We describe a case of a 61-year-old woman with amyopathic dermatomyositis (ADM), who developed rapidly progressive interstitial pneumonia and died of respiratory failure. An autopsy revealed interstitial pneumonia with diffuse alveolar damage, associated with infiltration of T cells, mostly positive for CD 8. The alveolar lining epithelial cells manifested the remarkable expression of immediate early/early antigen of human cytomegalovirus (HCMV). Moreover, the extract of the lung was transmittable of HCMV infection to cultured human embryo-fibroblasts in vitro. On the other hand, in the semi-quantitative analysis of HCMV genome, using laser-assisted microdissection, followed by PCR method, the genomic DNA in the alveolar lining epithelial cells was little detected in this case, although it was remarkable in the case of immunodeficiency with cytomegalovirus pneumonia. This case may be important to know the role of the immune response of host to HCMV infection on the development of rapidly progressive interstitial pneumonia.