Patients frequently present to multiple hospitals for acute care visits, resulting in incomplete medical records at any given site, and placing patients at risk for poor quality of care. Our objective was to determine the number of patients presenting for their acute care needs across multiple hospitals in Massachusetts over a three year period. There were 665,481 adult patients who presented to a median of 2 different hospitals (range 2-55) in the course of the study period. Integration of medical information across sites, such as through personally controlled health records, could improve the availability of medical information across sites of care.