Male guppies in wild Trinidadian populations devote a large proportion of their time to pursuing females, and females, as a result, are frequent targets of sneaky mating attempts. In this paper we demonstrate a cost, in terms of lost feeding opportunities, to these female recipients of sexual harassment. An experiment in pools of a Trinidadian stream manipulated sex ratio and fish density within the ranges naturally occurring in the system. We found that sexual harassment (from males) led to a 25% decrease in foraging beyond that which occurred as a result of female competition. Because the fecundity of female fish is a product of their feeding success, reductions in food intake have potentially serious fitness consequences.