Abstract: Objective To investigate the susceptibilities of human cytomegalovirus(HCMV) clinical isolates to ganciclovir(GCV) after hematopoietic stem cell transplantation in Guangzhou and preliminarily establish the experimental drug induced HCMV drug resistant strains. Methods Blood or urine samples were collected from patients receiving GCV therapy because of HCMV infection after hematopoietic stem cell transplantation HCMV clinical strains were isolated and identified by HELF cell culture method. Tissue cell infection median dose (TCID50) was calculated by reed-muench method. Drug susceptibility was determined by MTT assay. The laboratory strain tested at predetermined concentrations of GCV(1.5, 3,6,10,50, and 300 μmol/L). Results TCID50 values of eight HCMV clinical strains were 10-4.12/0.1 mL, 10-4.29/0.1 mL, 10-4.30/0.1 mL, 10-4.40/0.1 mL, 10-4.42/0.1 mL, 10-4.50/0.1 mL, 10-4.52/0.1 mL, 10-4.62/0.1 mL, respectively. 50% inhibitory concentrations (IC50) to GCV of eight HCMV clinical strains were from 1.89 μmol/L to 5.95 μmol/L. In the presence of 10 μmol/L GCV, emergence of drug resistance virus was observed initially (IC50=18.15 μmol/L) and viruses selected in the presence of 300 μmol/L GCV were highly resistant to GCV with 174-fold higher in IC50 (327.10 μmol/L). Conclusion The susceptibilities of HCMV clinical isolates to GCV were higher and clinical drug resistance strains were not found in this experiment. The GCV resistant HCMV laboratory strain was preliminarily established in vitro and could create conditions for the resistants tudy of HCMV.