The growing significance of unmanned aerial vehicles (UAVs) is attributed to their ability to maintain aerial positions and maneuver as needed to ensure the reliable communication with ground-based devices. This distinctive capability has attracted considerable research interest for positioning UAVs as strong candidates to establish ad hoc communication networks. UAVs could be stationed in the air and moved as necessary to sustain reliable communication with ground devices. This versatility enhances the utility of UAVs, particularly, in challenging terrains where the line-of-sight (LoS) connection is unattainable, the UAVs could be deployed to establish a direct link with communicating devices. This chapter analyzes a UAV/FSO relaying system with incorporating key features of UAVs in the modeling process. The DF relaying protocol is used to investigate the impact of various UAV factors such as probability of LoS, terrain, large- and small-scale fading along with the optical turbulence and pointing error on the FSO link.