The uptake rate of some sugars was demonstrated in human embryo fibroblasts following infection by human cytomegalovirus (HCMV) and a significant increase in glucose uptake was demonstrated. Quantitative and sequential analysis of glucose uptake during the HCMV replication cycle showed that the enhanced uptake began during the first 20 h after infection and occurred even when a high glucose level was constantly present in the medium. The increase in sugar uptake requires an active viral genome, de novo protein synthesis and seems to be dependent only on the early transcription of the viral genome, as it did occur when replication of the viral genome was limited (non-permissive cells or cells infected in the presence of DNA synthesis inhibitors).