This study reviews the evidence on the health and social effects of drinking kava; a water-based infusion of the roots of the kava plant. The approach included all empirical studies of the effects of kava published in 1987-2008 reporting health and social outcomes. The evidence was appraised on study design (level of evidence) and standard epidemiological criteria for causality. Key findings show causality indicated: scaly skin rash, weight loss, raised Gamma Glutamyl Transpeptidase liver enzyme levels, nausea, loss of appetite or indigestion; Association indicated but causality unclear: red sore eyes, impotence or loss of sexual drive, self-reported poor health, raised cholesterol, and loss of time and money, low motivation and 'slow/lazy' days following use, reduced alcohol consumption and related violence; Association hypothesized: fits or seizures, Melioidosis, Ischaemic Heart Disease, protective effects for cancer; No association indicated: cognitive performance; No association suggested: cognitive impairment, liver toxicity or permanent liver damage, other pneumonia; No association hypothesized: hallucinations. The health and social implications of chronic kava drinking can be significant for individuals and communities, although most effects of even heavy consumption appear to be reversible when consumption is stopped. An Australian-wide ban on commercial importation of kava has been in place since mid-2007, but there is no published literature to date on the impact of the ban. (Published Abstract) Tables and references