Studies on the effects of perfluorooctane sulfonic acid (PFOS) exposure on terrestrial invertebrates are very scarce. Here, we quantified the effects of PFOS on the number of offspring for two generations of Drosophila hydei Sturtevant 1921 (Diptera: Drosophilidae) reared in the laboratory. The first generation was exposed to a range of PFOS concentrations from 5 to 5,000 ng/ml and a control through their diet. For the second generation, offspring of the 50 ng/ml PFOS treatment and the control were further reared in a PFOS-free environment. For the first generation, the number of offspring decreased with increasing levels of PFOS contamination. Although the second generation was not exposed to PFOS, we still observed a reduction in the number of offspring when the parental flies were exposed to 50 ng/ml PFOS. The results of the current study indicate that the sensitivity to PFOS of D. hydei is several magnitudes higher than of the other terrestrial invertebrate species tested so far. This sensitivity falls within the concentration range detected in its natural food.