Background Measles virus is a highly prevalent neurotropic virus capable of causing persistent infections within the central nervous system. Methods We measured IgG class antibodies to measles in 820 individuals including 138 with recent onset psychosis, 378 with persistent schizophrenia, and 304 non-psychiatric controls. Levels of antibodies among the groups were compared by bivariate and by multivariate analyses and correlated with clinical and demographic variables. Results The level of measles antibodies in individuals with a recent onset of psychosis was greater than the level of antibodies in individuals with persistent schizophrenia or individuals without a history of a psychiatric disorder (p <.00001). The level of measles antibodies in the individuals with persistent schizophrenia was greater than the level of measles antibodies in the controls (p <.001). Recent onset of psychosis was associated with having elevated levels of measles antibodies, defined as the 90th percentile of the levels of the controls, with an odds ratio of 8.0 (95% CI 4.6, 14.0); persistent schizophrenia was associated with having this level with an odds ratio of 2.3 (95% CI 1.4, 3.7). Within the psychiatric groups, measles antibody levels were associated with age, race, and current treatment with the antipsychotic medication, olanzapine. Conclusions The reasons for elevated levels of measles antibodies in the psychiatric groups are not known with certainty and should be studied in prospective investigations.