This study aims to determine the effect of ownership structure on risk-taking behaviour among the companies listed on the Indonesia Stock Exchange in the period 2013 to 2015 with a total of 390 firm observations. Companies' risk-taking is measured through income volatility over five years. There are two types of corporate ownership structures investigated in this study: family ownership and foreign ownership. By using fixed effect panel regression, the results showed that both ownership structures have a significant negative effect upon the company's risk taking behaviour, which implies that family and foreign ownership can function effectively to mitigate excessive risk-taking behaviour in a company. Type of paper: Empirical