Abstarct: This study evaluates the effect of ownership status and conduct and performance on market share in chemical and refining industries in Iran; by using data from workshops with ten workers or more, in chemical and coke (fuel) manufacturing industries, oil and nuclear refineries between 2004-2013. Variables utilized in this study are market share, ownership intensity, value-added intensity, investment intensity, advertising intensity and R&D costs intensity. Dynamic Panel Data (DPD) method is used to estimate market share as a structural index for market. results showed that increase in private ownership in chemical and refining industries in Iran, raises the amount of industrial market share. In addition, more added values, investmentsand R&D in these industries, increase market share. Besides advertising costs, decrease the market.