This paper describes five working examples of how high speed digital fiber optic transmission systems are cun-ently being applied within CATV networks to deliver video, audio and data services for distribution into the cable network. These digital networks provide high signal performance (RS250C medium haul and short haul) and can process and transport the entire range of signals present within the CATV environment including: baseband video and audio, BTSC subcarrier audio, baseband and IF scrambled video, 64 QAM and 16-level VSB signals and low-speed asynchronous data. Also presented here is a review of the digital building blocks that comprise the network and the justifications for selecting digital transmission in each network.