Dual practice by surgery specialists is a widespread issue across health systems. This study aimed to determine the level of dual practice engagement and its related factors among Iran's surgery specialists.A pre-structured form was developed to collect the data about surgery specialists worked in all 925 Iran hospitals in 2016. The forms were sent to the hospitals via medical universities in each province. The data were merged at the national level and matched using medical council ID codes, national ID codes and eventually a combination of the first name, surname and father's name. Multilevel logistic regression was used to assessing the association between dual practice with study variables.Overall, 14931 surgeons were participated 93% response rate) and 6405 (57% of) engaged in DP on total. Urinary tract & genital and neurosurgery specialties had the highest rank with 69%. DP was more frequent in specialists with higher age and experience, populated provinces, higher deprivation, and share of private hospitals. Faculty physicians (OR=0.69), full-time geographic physicians (OR=0.17), specialists with more than 25 years' experience (OR=2.59) and age more than 40 yr (OR=1.3) had significant association with dual practice.Multi-approach strategy is needed to control dual practice through tax regulations, income cap, and limitations in work hours and number of visits in private sector.