Background. Human herpesvirus-6 (HHV-6) infection is ubiquitous in selected population with sero-prevalence of 60-80%. Little is known for that in China, except few sporadic studies. To understand prevalence of HHV-6 antibody in Chinese population,this seroepidemiological study was conducted.Methods. Sera were collected from 430 healthy persons and donors living in North China,and tested for HHV-6 antibodies using IFA with HHV-6 GS strain passaged on HSB-2 cells as antigen, and titer e-qual or higher than 1:10 was regarded as seropositive.Results. Of the 430 serum samples tested,297 (69.1%) were positive for HHV-6 IgG. Both seropositive rate and GMT in females were significantly higher than those in males,with X2 = 7. 05,P<0. 01 and F = 7.23,P<0. 01,respectively. Statistically significant difference in prevalence of HHV-6 antibody among various age groups was observed in both sexes,with X2=20. 08 and 20. 28,P = 0. 04,respectively,and young children had a higher titer than adults. But, no significant dif Background. Human herpesvirus-6 (HHV-6) infection is ubiquitous in selected population with sero-prevalence of 60-80%. Little is known for that in China, except few sporadic studies. To understand prevalence of HHV-6 antibody in Chinese population, this seroepidemiological study was conducted. Methods. Methods Sera were collected from 430 healthy persons and donors living in North China, and tested for HHV-6 antibodies using IFA with HHV-6 GS strain passaged on HSB-2 cells as antigen, and titer Of the 430 serum samples tested, 297 (69.1%) were positive for HHV-6 IgG. Both seropositive rate and GMT in females were significantly higher than those in males , with X2 = 7. 05, P <0.01 and F = 7.23, P <0.01, respectively. Statistically significant difference in prevalence of HHV-6 antibody among various age groups was observed in both sexes, with X2 = 20 . 08 and 20. 28, P = 0.04, respectively, and young children had a higher titer than adults. But, no significant dif