This study analyzes the effects of a mobile cardiovascular screening unit on the caseload of a 239-bed private hospital that specializes in cardiovascular services. In April 1985 Providence Hospital of Columbia, South Carolina began sending a mobile van with a technician and cardiovascular diagnostic equipment to seven hospitals outside the Columbia metropolitan area. During the first year of operation the mobile unit completed 787 tests on 735 patients. Comparing the first year of operation to the prior year, there was a 4.8 percent decrease in admissions to cardiology and a 42.1 percent increase in admissions to cardiovascular surgery. There was a 628 percent increase in outpatient tests performed on residents of the counties where the van operated when tests performed by van personnel were added to outpatient tests at the hospital. Thus, the mobile unit is an effective tool for increasing this hospital's market share for these procedures.