Previous studies have found that the use of social networking sites (SNSs) is associated with the user's positive outcomes such as perceived social support and psychological well-being (Ellison, Steinfield, & Lampe, 2007; Nabi, Prestin, & So, 2012). To seek those positive influences, those with health issues such as physical illness or mental illness actively use SNSs (e.g., Shpigelman & Gill, 2014a; Gowen, Deschaine, Gruttadara, & Markey, 2012). The first aim of this chapter is to describe previous studies on the use of SNSs by those with health issues such as mental illnesses, HIV/AIDS, cancer, intellectual disabilities, and diabetes. The second aim is to propose a new direction of research on the use of SNSs by those with health issues: the impact of stigma on communication on SNSs.