The progress in mobile devices and wireless communication technologies magnifies the importance of opportunistic networks like Mobile Ad-hoc NETworks (MANETs). In MANETs, information sharing is performed by distributing advertisements and queries. In order not to load the environment with unnecessary traffic, file advertisement and query resolution should be performed according to the interests of users. In this paper, we propose algorithms to identify and estimate users’ interests. Experimentations are conducted to evaluate the performanace of the proposed algorithms on a mobile phone and a PC.