In this paper we examine the effect of information on investment in self-protection. We show that the relationship between more information and investment in self-protection is ambiguous in general. If absolute risk aversion is constant, then investment in self-protection always decreases with a better information structure. We show that if we interpret the Precautionary Principle as requiring more self-protection today, it is difficult to accept it on the grounds of efficiency, except for a particular subset of information structures.