Understanding the prevalence and demographic correlates of physical activity is important for public health and epidemiological research. This analysis examines the association between acculturation and physical activity in a large (similar to 5,000) sample of Hispanic adults from the 2000 National Health Interview Survey. Scores for eight questions concerning language use were summed to produce an acculturation index. Factor analysis indicated that these questions assessed a single underlying construct. Self-reported adherence to recommendations concerning leisure time physical activity increased from 22.6% in the least acculturated tertile to 47% in the most acculturated tertile. In contrast, prevalence of walking or bicycling for errands decreased from 25.2 to 18.2%, and prevalence of standing or walking during most of the day decreased from 82.8 to 65.6% as acculturation increased. Thus, patterns of physical activity associated with leisure versus nonleisure time differed among Hispanics with varying acculturation levels. Alternatively, cultural factors may have differential effects on responses to questions concerning leisure and nonleisure time physical activity. In either case, assessing both types of activity is important for monitoring and understanding Hispanic health behaviors and interpreting epidemiological studies that involve physical activity in Hispanics. (Contains 5 tables.)