This study analyzed whether a children's hospital urgent care clinic helped increase market share. Patient demographics and utilization patterns between the suburban clinic and urban emergency department were compared over a three-year period (July 1999 to June 2002). Using data from a standardized billing form, all patient visits (clinic: 36,924; emergency department: 160,888) were analyzed. Variables included patient visitation data, age, gender, race, primary insurance carrier, primary diagnosis, and primary residence Zip code. Differences between the after-hours clinic and emergency department included: more private insurance coverage (83% and 35%, respectively); less no insurance/Medicaid/State Children's Health Insurance Program (SCHIP) coverage (16.4% and 55%, respectively); and more Caucasian patients (80% and 35%, respectively) at the off-site clinic; thus usage was more similar with that of a physician's office than an outpatient clinic. Symptoms seen in the after-hours clinic were primarily respiratory, ear, and throat related. In the emergency department, the symptoms were more varied, primarily febrile, respiratory, ear, throat, gastrointestinal, and urinary tract problems. There was a 3.6% increase in the number of visits in the after-hours clinic and a 1.6% decrease in the number of emergency department visits between year one and year three—data combined giving an overall 4.8% increase in the number of visits. Data show that the offsite urgent care clinic located in a suburban area increased the overall number of visits with a large number of well-insured patients. Additionally, this study provided data on where the clinic could expand medical care for the community.