Health care cost controls have focused on improving primary care access to avoid preventable and costly emergency department (ED) and inpatient (IP) admissions. Research on missed outpatient appointments has focused on ED and hospital admission follow-up rather than focusing on missed appointments as potentially leading to or being associated with ED and hospital admissions. One objective of this study is to describe the association of missed outpatient appointments with ED and IP stays while adjusting for demographic, payer type, and health status.