Twenty-three subjects were administered three doses of inactivated herpes simplex virus (HSV) type 2 (HSV-2)glycoprotein-subunit vaccine, with doses 2 and 3 being given four and 22 weeks after dose 1. Both HSV-neutralizing antibody and antibody effective in antibody-dependent cell-mediated cytotoxicity were detected in serum samples of 12 of the 13 initially seronegative subjects by week 8. The geometric mean titers of both antibody types decreased between weeks 8 and 22 but increased one week after dose 3. HSV-neutralizing antibody remained detectable in serum samples of seven of the 10 initially seronegative subjects assayed seven months after dose 3. Cell-mediated immunity was detected by lymphocyte transformation responses to HSV-2 after vaccine administration in 12 of the 13 initially seronegative subjects. Unlike humoral antibody, which waned over time, in vitro cell-mediated immume responses remained stable over the seven-month follow-up period after dose 3. This HSV-2-subunit vaccine is well tolerated and elicits both humoral and cell-mediated immune responses to HSV.