The purpose of this article is to analyse the influence of corporate insider ownership of shares on the performance of companies in the retail industry. Prior research examined the relationship between insider ownership and firm values measured by Tobin's Q. In this article, we focus on the relationship between insider ownership and efficiencies measured using Data Envelopment Analysis (DEA). To estimate efficiency using DEA, we treat employees, total earning assets (that includes property, plant and equipment and current assets), inventory and selling, general and administrative expenses as inputs and sales, income before extraordinary items and stock market values as outputs. This study confirms positive relationship between insider ownership and efficiencies of companies in the retail industry.