: Burnout, which is an emerging challenge in health systems, is very common among primary health care (PHC) workers. The aim of this study was to investigate the level of burnout among PHC workers, and its predictive factors, in a region in the west of Iran.In this cross-sectional study, all the health network staff (n = 539) were enrolled. The data collection instrument was the Maslach Burnout Inventory (MBI), which consists of 22 items and the three subscales of emotional exhaustion (EE), depersonalization (DP), and personal achievement (PA). High scores in EE and DP and low scores in PA are indicative of high burnout. Logistic regression was used to determine the predictors of high burnout. The data were analyzed using SPSS version 16. The findings showed that 90.5% of the staff had high DP, 55.3% had high EE, and 98.9% had low PA scores. Also, 52.9% (277 people) of the staff suffered from high burnout. Single people (OR = 3.33), less experienced employees (OR = 9.09), people aged over 35 years (OR = 2.35), physicians (OR = 1.72), and staff with permanent employment (OR = 5.0) were more likely to suffer high levels of burnout. We conclude that burnout is a common problem in PHC workers. Less experienced, younger, single employees and physicians were more at risk of suffering from high burnout. Preventive measures, such as strengthening social skills, communication competencies, and coping strategies, and reduction of risk factors such as job stress, are suggested for reducing employees’ risk of burnout.