Women in Iran face widespread challenges in participating in the workforce. The rate for Iranian women’s participation in the labor force has stayed constant at around 11% over the past decades. The International Labor Organization (2019) estimates that women in Iran earn 18%, on average, of the male wage. This paper examines the wage gap in Iran using the Iran annual Household, Expenditure, and Income Survey (HEIS) from 1994 to 2019. To understand the factors behind the gender pay gap, I use Oaxaca and Ransom’s (1994) methodology to decompose the wage gap into factors due to different characteristics of men and women and aspects of direct inequality of treatment. My results indicate that education, industry, private versus public sector, region, occupation, and occupational segregation are potentially significant sources of the wage gap against women in Iran.