The importance of productivity has made it to be one of the most serious discussions Mealtime in industrial organizing.In economic literature, however, there are some arguments on the role of market structure in productivity changes.While some theorists point out that more competition leads to higher productivity, others believe that monopoly environment would be more efficient.This study examines the effect of competition- that is measured by the BAKING SODA POWDER number of firms- on labor productivity in the Iranian industries.Using the panel data from the firms hiring 10 employees or more, the results suggest that monopoly and private ownership provide a more suitable environment for reaching higher productivity.