Background/Purpose: Physical inactivity is associated with greater risk of cardiovascular disease, diabetes mellitus, some cancers, as well as many of the risk factors for poor health.  Despite these well known associations, many Americans remain sedentary.  With this understanding, it is imperative for health professionals to recognize which subgroups of the population are at greatest risk for being physically inactive.  The purpose of this study was threefold.  First, the study examined the prevalence estimates of no leisure-time physical activity (LTPA) within sociodemographic subgroups of US adults.  Second, the study identified those adults who were more likely to indicate no LTPA by estimating crude odds ratios (ORs) within each of the sociodemographic subgroups.  Third, the study made statistical adjustments to the ORs by use of multiple logistic regression to examine if high risk groups remained significant.  Method: Data for this study came from the 2005-2006 National Health and Nutrition Examination Survey (NHANES).  A total of 5,367 adults ages 18 years or older (male = 2,578 and female = 2,789) were included in the analysis.  LTPA was assessed by answers to two questions asking respondents if they participated in moderate or vigorous activities.  Those respondents answering “no” to both questions were considered to be participating in no LTPA.  The sociodemographic variables used were gender (male/female), age (18-34/35-59/60+ yr), race (White/Black/Mexican/other Hispanic/other), marital status (never married/separated or divorced/widowed), income (65+/64.9-45/44.9-25/24.9-15/<15k), and education (college graduate/some college or AA degree/high school graduate/<high school graduate).  The first group of each variable served as the reference group.  Analysis/Results: The SAS 9.1 SURVEYFREQ and SURVEYLOGISTIC procedures were used for prevalence estimates, ORs, and 95% confidence intervals (CIs).  Overall, 30.5% (95% CI: 27.5-33.6) of adults reported no LTPA.  The subgroups with the highest levels of no LTPA were 60+ yr (41.3%, 95% CI: 35.8-46.8), Mexican (46.7%, 95% CI: 42.2-51.2), widowed (47.9%, 95% CI: 40.9-54.8), 24.9-15k (43.3%, 95% CI: 38.2-48.4), and <high school graduate (51.2%, 95% CI: 46.0-56.4).  Each of the crude ORs lowered after adjustment, however, remained strong and significant:  60+ yr (OR=2.17, 95% CI: 1.62-2.90), Mexican (OR=1.59, 95% CI: 1.17-2.16), widowed (OR=1.55, 95% CI: 1.07-2.26), 24.9-15k (OR=1.68, 95% CI: 1.47-1.93), and <high school graduate (OR=4.71, 95% CI: 3.23-6.89).  Conclusions: The current study found that the prevalence of no LTPA reported by adults is dependent on specific sociodemographic characteristics.  This study provides information to help in the planning stages of interventions aimed at increasing LTPA among adults.