Objective: Although the majority of women with serious mental illnesses (SMI) are mothers, limited research is available on the relationship between maternal SMI and pediatric health care use. Adherence with preventive care is associated not only with improved children's health and well-being but also decreased costs to the health care system. This study examines the relationship between maternal psychotic disorders (PDs) and pediatric health care. Method: This retrospective secondary analysis of Medicaid claims compares age cohorts of children (0 to 4 years) of mothers with and without PDs. Bivariate and multivariate logistic regression models are used to examine established measures of pediatric preventive care and emergency department (ED) care among 297,866 mother-child dyads. Results: Adherence to preventive care guidelines ranged from 19% to 34% among mothers with PDs and from 24% to 32% among mothers without PDs. Mothers with PDs are 1.41 times more likely to have at least one preventive care visit in Year 0-1 (95% CI [1.20, 1.65], p < 0.0001); 0.67 times less likely to have at least one visit in Year 3-4 (95 % CI [0.54, 0.82], p < .0001); and significantly more likely to have high ED reliance for their children ages 0 to 2 years (p < .01). Conclusions: Few differences existed in pediatric health care use among Medicaid-insured mothers with and without PDs. Although preventive pediatric health care use among mothers with PDs is comparable with that of mothers without PDs, mothers with mental illness could still benefit from targeted strategies to reduce ED reliance for their young children (0 to 2 years). Social work involvement with all families living in poverty should help these families access and use preventive care for young children.