BackgroundIncreasing level of physical activity (PA) among working population is of particular importance, because of the high return of investment on employees’ PA. This study was aimed to investigate socioeconomic inequalities in Health-Enhancing Physical Activity (HEPA) among employees of a Medical Sciences University in Iran.MethodsData were extracted from the SHAHWAR Cohort study in Iran. Concentration index (C) and Wagstaff decomposition techniques were applied to determine socioeconomic inequality in the study outcomes and its contributors, respectively.ResultsNearly half of the university employees (44.6%) had poor HEPA, and employees with high socioeconomic status (SES) suffered more from it (C = 0.109; 95% CI: 0.075, 0.143). Also, we found while poor work-related PA (C = 0.175; 95% CI: 0.142, 0.209) and poor transport-related PA (C = 0.081, 95% CI: 0.047, 0.115) were more concentrated among high-SES employees, low-SES employees more affected by the poor PA at leisure time (C = -0.180; 95% CI: -0.213, -0.146). Shift working, and having higher SES and subjective social status were the main factors that positively contributed to the measured inequality in employees’ poor HEPA by 33%, 31.7%, and 29%, respectively, whereas, having a married life had a negative contribution of -39.1%. The measured inequality in poor leisure-time PA was mainly attributable to SES, having a married life, urban residency, and female gender by 58.1%, 32.5%, 28.5%, and -32.6%, respectively. SES, urban residency, shift working, and female gender, with the contributions of 42%, 33.5%, 21.6%, and -17.3%, respectively, were the main contributors of poor work-related PA inequality. Urban residency, having a married life, SES, and subjective social status mainly contributed to the inequality of poor transport-related PA by 82.9%, -58.7%, 36.3%, and 33.5%, respectively, followed by using a personal car (12.3%) and female gender (11.3%).ConclusionsTo reduce the measured inequalities in employees’ PA, workplace health promotion programs should aim to educate and support male, urban resident, high-SES, high-social-class, and non-shift work employees to increase their PA at workplace, and female, married, rural resident, and low-SES employees to increase their leisure-time PA. Active transportation can be promoted among female, married, urban resident, high-SES, and high-social-class employees and those use a personal car.