After the introduction of the National Health Insurance have gradually increased the competition in the medical market. It is more important to make use of marketing to promote hospital image. This research tries to understand the key factors that affect outpatient to hospital. Interviews in person were performed in 1998 with 300 outpatients Above selected from three hospital-National Cheng Kung University Hospital、 CHI MEI FOUNTATION Hospital、 Provincial TAINAN Hospital in TAINAN METROPLIS. The results showed that the important factors that effect outpatient are the medical care quality and the equipment of hospital. The expert commendation is more important than the commendation of relatives or friend. To hospital promotion, outpatient believe and pay attention to more than to approve of.