Methods and apparatus to maintain audience privacy while determining viewing of video-on-demand (VOD) programs are disclosed. An example method disclosed herein comprises obtaining subscriber metering data from a site metering device monitoring presentation of VOD content at a first subscriber site, obtaining server metering data from a VOD server, the server metering data including identification information for a plurality of subscriber sites to identify particular VOD content provided uniquely to each of the subscriber sites, the identification information manipulated to preserve anonymity of the plurality of subscriber sites, manipulating at least a portion of the subscriber metering data to determine a first manipulated identifier to identify the first subscriber site, and using the first manipulated identifier to cross-reference the manipulated identification information included in the server metering data to merge the subscriber metering data and the portion of the server metering data uniquely associated with the first subscriber site.