Mobile social networking applications are getting increasingly popular among today’s mobile applications. Mobile users find their old or new friends anywhere or anytime through mobile social network (MSN) services. MSN uses matchmaking mechanisms to discover mutual interests among different people. To discover friends in MSN, a user must share his/her private information which can be a risk for his /her personal privacy as this information can be learned by a malicious or semi honest user. In this paper we give a brief survey on MSN that includes MSN categories, components, architecture and applications. In the rest of the paper we discuss the matchmaking protocols. Finally we give some suggestions to improve the previous protocols.