Based on sequence variation of the glycoprotein B (gB) gene, human cytomegalovirus (HCMV) strains can be classified into four gB genotypes. In a previous study of bone marrow transplant recipients, infection with the gB type 1 correlated with a more favorable clinical outcome than infection with the gB types 2, 3, or 4. The gB type was determined in 60 renal transplant and in 47 bone marrow transplant recipients using PCR and restriction analysis. All HCMV variants in patient specimens could be assigned to one of the four previously described gB types. Two or more specimens obtained from 39 patients were analysed; in 31 of these patients the gB type was the same in all samples. The gB type did not correlate with the clinical outcome or the level of viremia in renal transplant recipients.