Human metapneumovirus (hMPV) causes both upper and lower respiratory tract infection worldwide. Because little is known about the estimated level of exposure to hMPV in Taiwan, data for 1999 are presented. One thousand one hundred twenty sera from otherwise healthy community-based subjects aged 1 month to 99 years were tested in an enzyme-linked immunosorbent assay; the proportion of seropositive individuals was 68.1%. Moreover, 53.2% of preschool children were seronegative, whereas 88.3% of school-aged individuals and 93.7% of adults had antibodies to hMPV. In summary, the present study provides an earlier evidence of a high rate of exposure to hMPV characterized the seroprevalence among Taiwanese individuals in 1999. In addition, our findings suggest that preschool children in particular would benefit from vaccination against hMPV.