Objectives To describe the physical activity profile of Saudi adults living in Riyadh, using the International Physical Activity Questionnaire (IPAQ) short-version telephone format. Methods Physical activity was assessed using the official Arabic short form of IPAQ, intended for use in telephone interview. The instrument asks for times spent in walking, moderate- and vigorous-intensity physical activity of at least 10 min duration. The sample consisted of 1616 Saudis, between 15 and 78 years of age, living in Riyadh. Participants were drawn from a list of names in the telephone book using a simple random method. Telephone interviews were administered during the spring of 2003 by trained male interviewers. Results The final sample size was 1064 Saudi males and females (response rate of 66%), with males comprising about 66% of the respondents. Over 43% of Saudis did not participate in any type of moderate-intensity physical activity lasting for at least 10 min. More than 72% of the sample did not engage in any type of vigorous-intensity physical activity lasting for at least 10 min. The proportion of Saudis who walked for 150 min or more per week was 33.3%. Females were engaged more in moderate physical activity than males, whereas males participated more in vigorous activity compared with females. Activity levels did not show significant relationships with education level or job hours per week. Based on the three activity categories established by IPAQ, 40.6% of Saudis were inactive, 34.3% were minimally active and 25.1% were physically active. Physical inactivity increased with advancing age. Conclusion The data suggest that the prevalence of physical inactivity among Saudis adults is relatively high. Efforts are needed to encourage Saudis to be more physically active, with the goal of increasing the proportion of Saudis engaging in health-enhancing physical activity.