Aedes aegypti mosquitoes transmit numerous pathogens that pose significant risks to human health despite current interventions. Sex-specific molecules essential for reproduction are valuable potential targets for the suppression of mosquito populations and, by extension, the diseases they spread. During mating, males transfer seminal fluid proteins (SFPs) to females within their ejaculate which induce physiological and behavioral changes, collectively referred to as the female post-mating response (PMR), that are required for optimal fertility. Reproductive senescence has profound impacts on male fertility and SFP composition in several species, which in turn affects the strength of the female PMR. In A. aegypti, old males fail to induce some SFP-dependent female PMRs suggesting that changes in the SFP proteome may be occurring, but this has not been directly investigated. Here, we used whole animal heavy labeling and LC-MS/MS to detect protein abundance changes between old and young male ejaculates. A total of 83 ejaculate proteins, including 22 SFPs, displayed a 2-fold or greater change in abundance compared to optimally fertile, young males. Our findings suggest A. aegypti ejaculate protein composition is altered by reproductive aging, and we identify SFP candidates that may effect female PMRs.