We investigated levels of maternal cytokines in late pregnancy in relation to the subsequent development of adult schizophrenia and other psychoses in their offspring. The sample included the mothers of 27 adults with schizophrenia and other psychotic illnesses and 50 matched unaffected controls from the Providence cohort of the Collaborative Perinatal Project. Serum samples were analyzed for interleukin 1 beta (IL-1-β), interleukin 2 (IL-2), interleukin 6 (IL-6), interleukin 8 (IL-8), and tumor necrosis factor alpha (TNF-α) by enzyme immunoassay. Maternal levels of TNF-α were significantly elevated among the case series (t = 2.22, p = .04), with evidence of increasing odds of psychosis in relation to higher cytokine levels. We did not find significant differences between case and control mothers in the serum levels of IL-1, IL-2, IL-6, or IL-8. These data support previous clinical investigations reporting maternal infections during pregnancy as a potential risk factor for psychotic illness among offspring.