We present the first study to directly measure the relative reproductive success (RRS) of hatchery- and natural-origin Pink Salmon (Oncorhynchus gorbuscha). We examined both odd- and even-year lineages for two streams in Prince William Sound, Alaska (PWS) to provide pseudo-replicate measures of RRS. Reproductive success, measured as adult progeny that return and die in the stream, was significantly lower for hatchery-origin versus natural-origin parents from both lineages. However, while reproductive success was significantly lower for hatchery females in both streams and lineages, the reductions in male reproductive success were not always statistically significant. Generalized linear modeling indicated that reproductive success was lower in hatchery-origin fish after accounting for covariates such as sample date (run timing), sample location within the stream, and fish length. These are the first in a series of RRS analyses under the Alaska Hatchery Research Program (AHRP), which will ultimately include replicate analyses in other streams that will provide more power to investigate cross-type effects (matings between natural- and hatchery-origin fish, and the potential to explore inter-generational effects generations to determine whether decreased reproductive success is ephemeral (effects a single generation) or long-term (effects multiple generations). If reductions in fitness are replicated, important questions will remain regarding the mechanisms driving the effect and its persistence into future generations. Identifying driving mechanisms behind reductions in fitness and the potential for persistent effects across generations will be important to inform policy makers on how best to balance the economic value of hatchery programs with the potential for risk to wild stocks.