This paper investigates informative price advertising in an established-product Hotelling duopoly where firms compete for shares of a fixed market. Prices are uncertain because firms’ costs are private information. For a sufficiently low cost of advertising, advertising necessarily arises in equilibrium. Also, the less balanced the initial distributions over costs, the greater the potential for informative advertising. Moreover, whenever firms use informative advertising, it increases the firms’ expected profits, and social welfare, relative to the outcome without advertising.