There are a several published guidelines recommending treatment pathways for patients with primary spontaneous pneumothorax (PSP). Little is known about how these patients are actually treated in Australia. The aim of this study was to establish treatment patterns for Australian patients with PSP. This was a multicentre retrospective observational study conducted at 19 emergency departments across Australia of adult patients with PSP presenting in the calendar year 2005. In Australia, there is considerable deviation from published guidelines for the management of PSP. In light of the lack of high-quality evidence to assist in choosing treatment approaches, a randomized controlled trial of management strategies is recommended.