The local cellular immune response to herpes simplex virus (HSV) is important in the control of recurrent HSV infection. The antiviral functions of infiltrating CD4-bearing T cells may include cytotoxicity, inhibition of viral growth, lymphokine secretion, and support of humoral and CD8 responses. The antigens recognized by many HSV-specific CD4 T cells localizing to genital HSV-2 lesions are unknown. T cells recognizing antigens encoded within map units 0. 67 to 0.73 of HSV DNA are frequently recovered from herpetic lesions. Expression cloning with this region of DNA now shows that tegument protein VP22 and the viral dUTPase, encoded by genes UL49 and UL50, respectively, are T-cell antigens. Separate epitopes in VP22 were defined for T-cell clones from each of three patients. Reactivity with the tegument protein encoded by UL21 was identified for an additional patient. Three new epitopes were identified in VP16, a tegument protein associated with VP22. Some tegument-specific CD4 T-cell clones exhibited cytotoxic activity against HSV-infected cells. These results suggest that herpes simplex tegument proteins are processed for antigen presentation in vivo and are possible candidate compounds for herpes simplex vaccines.