OBJECTIVE: This study evaluated the benefit of consulting a statewide immunization registry for inner-city infants whose immunizations appeared, after single-site chart review, to have been delayed.

METHODS: We prospectively enrolled 315 newborns in 3 inner-city pediatric clinics. When the infants turned 7 months old, we obtained immunization data from clinic charts and the state registry.

RESULTS: On the basis of chart review, 147 infants (47%) were assessed to be delayed in their immunizations; of these, registry data revealed that 28 (19%) had received additional immunizations and 15 (10%) were actually up to date.

CONCLUSIONS: A statewide registry can capture immunizations from multiple sources, improving accurate determination of immunization rates in a mobile, inner-city population.