The aim of this paper is to present a study for the communication patterns evident in computer mediated communication in e-learning online communities. For the first time in this paper a list of factors affecting communication patterns within online communities is presented. A key concern of the study is twofold: first to define the correlation between patterns of communication and the affecting factors and second to suggesting criteria for designing successful learning activities. This study is concerned with an initial analysis of student interaction in three residential modules (approximately 1500 posts) that is currently followed by the analysis of threaded discussions of 32 online modules of a distance education programme.