MTBE, a gasoline oxygenate, has contaminated drinking water sources for many years. Carcinogenicity studies conducted in animals in the 1990s raised concerns of potential human health risks. Recent industry-sponsored studies have confirmed the carcinogenic effects of this agent and have identified additional sites of tumor induction (i.e., brain). However, the petroleum industry has attempted to portray these recent findings as demonstrating either no effect or no concern for humans. Our paper briefly summarizes the new findings and puts into perspective the totality of carcinogenic effects and health risks on this environmental chemical.