Background: This study compared levels of physical activity (PA) and sedentary behavior (SB) in adults with and without chronicdiseases or multimorbidity, acknowledging sociodemographic factors. Methods: A cross-sectional analysis was conducted with datafrom 27,890 participants (52% women), aged 50–64, from the Swedish CArdioPulmonary bioImage Study cohort. Over 1500chronic diseases were included and categorized into chronic disease and multimorbidity groups. Chronic diseases were retrieved fromnational registries, using International Classification of Disease codes. PA and SB were measured with a triaxial hip-wornaccelerometer, over 7 consecutive days. General linear models were used to calculate estimated means for daily time spent in light-intensity PA (LIPA), moderate- to vigorous-intensity PA and SB. Results: Time spent in LIPA, moderate- to vigorous-intensity PA,and SB did not differ between individuals in a chronic disease group and individuals without chronic diseases. Individuals living withany multimorbidity spent less time in moderate- to vigorous-intensity PA than participants without chronic diseases. Individualsliving with 4 or more chronic diseases spent more time sedentary than individuals without chronic diseases. Women spent more timein LIPA and less time in SB than men, regardless of chronic disease or multimorbidity. Individuals with less education spent moretime in LIPA and less time in SB than individuals with more education, regardless of chronic disease or multimorbidity. Conclusions:When using an extensive set of chronic diseases, marginal differences in PA and SB were seen between individuals living with andwithout chronic diseases. PA and SB seem to significantly differ by sex and education, rather than living with chronic disease.