Irukandji syndrome is a poorly defined set of symptoms that occur after envenoming by certain species of jellyfish, primarily cubozoans or 'box jellyfish'. Envenomed victims can show symptoms ranging from headaches, severe pain, nausea and vomiting to pulmonary oedema, cardiac failure and severe hypertension resulting in death. Historically, this syndrome appears to have been misdiagnosed and reported cases are undoubtedly a significant underestimation of the prevalence of this syndrome. The variation in symptoms has resulted in a myriad of treatments though none has been established as definitive. Effective pain relief with opioids is the most immediate priority. Although the annual numbers of envenomations are generally low, the associated financial costs of this envenomation may be comparatively high, with suggestions that it could run to millions of dollars per season in northern Australia alone. The syndrome has been well documented from many areas along the east coast of northern Australia, leading to the belief that it is an Australian oddity. However, with an increase in medical knowledge and improved diagnosis of the condition, it appears that envenomations causing Irukandji syndrome are an increasing marine problem worldwide.