Amazon River dolphins are endemic throughout the Amazon River watershed. Field studies of Amazon River dolphins are incredibly challenging due to the lack of a prominent dorsal fin, the dolphins’ shallow surfacing behavior, the tendency of the dolphins to swim among trees during high water season, and the opaque waters that these dolphins inhabit. The only reliable study that has investigated Amazon River dolphin sexual dimorphism was conducted on a small population of dolphins in Brazil, finding that males were approximately 16% longer and 55% heavier than females. The current study investigated dolphin lengths and widths using drone videos made in the Peruvian Amazon to evaluate the possibility of sexual dimorphism. The data collected suggests that there is sexual dimorphism in the populations sampled in Peru. Furthermore, if this is accepted, then the groups surveyed contained both males and females. In addition, one of the dolphins sampled may have been pregnant. Although this study was limited by a sample size of 40 dolphins, it suggests that the use of drones to evaluate Amazon River dolphin population demographics and health may be a good tool.