Neopterin, a marker of cellular immune activation, was elevated in patients who had cervical cancer in previous studies. To examine neopterin in the presence of precursors to cervical cancer (i.e., cervical intraepithelial neoplasia) we measured serum levels in 185 colposcopy patients in Jamaica, a country with high cervical cancer incidence, and in 72 age-matched Jamaican women selected from a large population-based sample. We also measured serum levels of beta-2-microglobulin, another commonly used marker of immune activation. Neopterin and beta-2-microglobulin levels were not elevated in colposcopy patients; neither were they related to severity of cervical neoplasia. In multivariable analysis, neither adjustments for detection of cervical human papillomavirus DNA by PCR nor detection of antibodies to human T-cell lymphotropic virus type I (a retrovirus endemic to Jamaica) altered our findings. The absence of a serologically detectable increase in cellular immune activation linked to cervical intraepithelial neoplasia suggests that the immunological response to cervical intraepithelial neoplasia does not involve substantial systemic cellular immune activation.