Objective To assess the physical activity of working residents of Warsaw aged 20–69 years, as well as to identify the socio-demographic factors associated with their levels of physical activity. Material and Methods The study involved 2,544 working residents of Warsaw aged 20–69 years. The short version of the IPAQ was applied and four physical activity levels (insufficient, sufficient, augmented, high) were distinguished. The relationships between physical activity and gender, age, BMI, education, economic and martial status as well as participation in recreation were determined. Results High levels of physical activity were reached by 8% of respondents, 22% achieved augmented level, 32% were sufficiently and 32% insufficiently active. Out of 2544 studied subjects, 6% declared complete sedentariness. Females were, as compared to males, more frequently (p<0.05) insufficiently active (35.9 vs. 31.9%). In obese and overweight subjects insufficient physical activity predominated (42.9 and 36.2%, respectively) and was significantly more frequent than in subjects with normal BMI (31.0%). Moreover, the subjects living in partner relationships were significantly (p<0.05) more frequently insufficiently active than those staying single (36.3 vs. 30.3%). Respondents who declared regular participation in leisure activities were less frequently insufficiently active (20.0%) and more frequently met the criteria of sufficient (37.6%), augmented (28.0%) or high (14.4%) level of physical activity. No significant effects were found with respect to education of respondents. Conclusions Prophylactic schedules associated with the improvement of physical activity level should be addressed particularly to females, people taking up recreation occasionally or to those not involved in recreation at all, living in partner relationships, youngest (21–30 years), in obese and overweight and in the lowest economic category.