There has been a rapid uptake of the use of online social networking services, and more recently their usage for health-related communication is also being researched and trialed. Twitter, a widely used micro-blogging service, has significant potential for the communication and sharing of up-to-date health information particularly with health consumers. In this paper a sample of 114 Australian health-related organizations’ Twitter accounts were identified, that matched inclusion criteria of a significant number of followers and activity. The 114 accounts’ micro-blog postings over a defined period of time were systematically analyzed, with a total of over 4,700 tweets retrieved, examined and manually categorized. This work analyzes Australian health-related micro-blog usage both in terms of health condition areas and types of micro-blog postings, including explanatory discussion of the outcomes and provides a case study in relation to re-tweeting of public health advice tweets. The work contributes to the literature by providing insights into the characteristics of community-wide health information dissemination via social media.