A retrospective analysis of cytomegalovirus (CMV) genotype was conducted on 281 CMV isolates obtained from marrow transplant recipients. The genotyping was based on sequence variations in the gene encoding envelope glycoprotein B (gB) as detected by restriction analysis of polymerase chain reaction (PCR)-amplified gB DNA. Among all isolates studied, the distribution of gB types 1-4 was 48.4%, 16.4%, 24.6%, and 8.2%, respectively, with only 2.5% of all isolates containing more than one gB type. The association of gB types with acute graft-versus-host-disease (GVHD) and death related to myelosuppression was examined using appropriate multivariable regression models. Covariables in addition to gB type included underlying disease type, donor-recipient HLA matching, donor CMV serostatus, and age as a continuous variable. Death associated with myelosuppression occurred in 2.9% or 4 of 136 patients with gB1, 0% or 0 of 46 patients with gB2, 21.7% or 15 of 69 patients with gB3, and 17.4% or four of 23 patients with gB4. The significant association of CMV gB type with death due to myelosuppression was maintained in a multivariable analysis (P < .001). In addition, the data also suggested that gB types 3 and 4 may be associated with a reduced hazard of grades II to IV acute GVHD.