Chemokine and chemokine receptor interactions may have important roles in leukocyte migration to specific immune reaction sites. Recently, it has been reported that CXC chemokine receptor (CXCR) 3 and CC chemokine receptor (CCR) 5 were preferentially expressed on T_h1 cells, and CCR3 and CCR4 were preferentially expressed on T_h2 cells. To investigate chemokine receptor expression by T_h subsets in vivo, we analyzed cytokine (IL-2, IL-4 and IFN-γ) and chemokine receptor (CXCR3, CXCR4, CCR3, CCR4 and CCR5) mRNA expression by individual peripheral CD4⁺ memory T cells after short-term stimulation, employing a single-cell RT-PCR method. This ex vivo analysis shows that the frequencies of cells expressing chemokine receptor mRNA were not significantly different between T_h1 and T_h2 cells in normal peripheral blood. To assess a potential role of in vivo stimulation, we also analyzed unstimulated rheumatoid arthritis synovial CD4⁺ memory T cells. CXCR3, CXCR4, CCR3 and CCR5 expression was detected by individual synovial T cells, but the frequencies of chemokine receptor mRNA were not clearly different between T_h1 and non-T_h1 cells defined by expression of IFN-γ or lymphotoxin-α mRNA in all RA patients. These data suggest that chemokine receptor expression does not identify individual memory T cells producing T_h-defining cytokines and therefore chemokine receptor expression cannot be a marker for T_h1 or T_h2 cells in vivo.