Methods and apparatus to determine audience viewing of video-on-demand programs are disclosed. An example method disclosed herein to monitor presentation of video-on-demand content comprises obtaining server metering data determined using a server metering device in communication with a video-on-demand server, the video-on-demand server to provide the video-on-demand content specifically to a first subscriber site among a plurality of subscriber sites, obtaining subscriber metering data corresponding to media content presented at the first subscriber site, the subscriber metering data determined using a site metering device different from the server metering device, and combining the subscriber metering data and the server metering data to monitor the video-on-demand content provided specifically to the first subscriber site.