The aim was to study the association of CD150 expression in peripheral blood mononuclear cells (PBMCs) with response to hepatitis B (HB) vaccination. Heparinized blood drawn from non-responders and responders was used to obtain PBMCs. Out of 460 adult healthy males and non-pregnant females, 27 subjects who were negative for HB markers were defined as non-responders (15 males and 12 females, aged 21-47 years). Among subjects who were anti-HB positive, 27 subjects were randomly chosen as responders (16 males and 11 females, aged 20-48 years). The isolated PBMCs were cultured and induced with recombinant HB surface antigen (rHBsAg) or phytohaemaglutinin (PHA). The expression of CD150 was then analyzed using flow cytometry. The levels of CD150 in both PBMC (t = 2.086, P = 0.044) and CD3+CD4+ cells (t = 2.221, P = 0.032) in non-responders to the hepatitis B vaccine were found to be significantly higher than those in the responders when the cells were induced with rHBsAg, while the level of CD150 in CD3+CD4- cells in non-responders were not significantly different from the responders. However, no significant difference was found in the level of CD150 in CD3+CD4+ cells or CD3+CD4- cells between non-responders and responders when the cells were induced with PHA. Therefore, CD150 may directly induce the proliferation of CD4+ and play a role in non-response to HB vaccination.