We investigated measles humoral immunity levels in a cohort of HIV-infected adult patients in France and attempted to identify risk factors for antimeasles antibodies seronegativity. Being born after 1983 [odds ratio (OR) 4.40; 95% confidence interval (95% CI) 1.26-14.09; P = 0.0013] and a nadir CD4⁺ cell count below 100 cells/μl (OR 4.79; 95% CI 1.61-14.82; P = 0.0048) were the two factors independently associated with measles seronegativity. Systematic measles antibody screening should be performed in HIV-infected individuals born in the era of measles vaccination (after 1983 in France).