To explore the extent of cross-border care seeking among Canadians, we analyzed the growth and distribution of Ontario Health Insurance Plan expenditures for medical care services provided in the United States to Ontario residents from 1987 to 1995. Although total out-of-province spending is low relative to in-province spending, there is evidence of cross-border care seeking for cardiovascular and orthopedic procedures, mental health services, and cancer treatments. However, combined with a preliminary investigation of cross-border patient care seeking using nonpublic funding sources, these analyses do not support the perception of widespread cross-border medical care seeking by Ontario residents.