The objective is to identify the action of capital markets, through the variation of stock returns, compared to the disclosure of oil spills caused by oil companies in the industry. The research was conducted from the event study methodology. The selected sample of events makes thirty four companies in the world oil industry, Petrobras, British Petroleum, Chevron and Shell, between 2000 and 2010. The results showed that the announcement of environmental accidents caused negative reactions in prices and stock returns. The analysis showed that environmental events have an impact on the value of companies, however was observed that information about an oil spill takes several days to be refl ected in stock price price, disagreeing with points made elsewhere (TAKAMATSU; COLAUTO; LAMOUNIER, 2008; CAMARGOS; BARBOSA, 2003), which indicated that the market reacts quickly to the events of an accounting nature.