Scholarly research on computer-mediated communication discourse has mainly centred upon the linguistic characteristics of emails, focusing on the formal and informal features and the orality involved in this form of communication. This paper presents a new insight into the study of computer-mediated communication (CMC) by analysing a fairly recent genre of computer-mediated communication, comments posted on the new social networking websites. The research undertaken examines the comments published on the official Facebook sites of some universities to observe the level of formality/informality of online communication in English. The distinction between online writings by native and non-native speakers of English has been considered as well. The study focuses on the formulae of etiquette and protocol used for salutation, opening, pre-closing and closing as an indicator of the degree of orality and informality in online writing. Data reveal that, in the specific context of the university, the use of Facebook is not conventionalised, as the comments posted on Facebook present important stylistic variations. Moreover, in most instances non-native speakers of English display more formal traits than native speakers when communicating electronically on social networking sites in the academic world.