BACKGROUND: The World Wide Web has become a widely utilized source of health information. Although the frequency of health related queries is impressive, the demographics associated with patients making queries has not been clearly delineated. OBJECTIVE: This study's objective was to determine health related Internet usage patterns of family medicine patients. METHODS: Internet use among 824 eligible patients 18 years or older attending seven university based family practice clinics during a two week period in November of 1999 was studied. The survey instrument included 10 items and was designed to collect data in less than five minutes using a paper and pencil format. Statistical significance associated with intended Web site use was computed using a multiple logistic regression model. RESULTS: A response rate of 72.2% was observed with 63.1% being females and 36.9% being males. The mean and median age were 44.0 and 45.7 years, respectively. A steady decline in intended Web site use was observed with advancing age with significant differences observed above 65 years (OR = 0.30; 95% CI = 0.14 - 0.64; p< .002). Other significant findings associated with intended use of a Web site by clinic based patients included having a home computer (OR = 1.99; 95%, CI = 1.05 - 3.76; p