During the study's first stage, 284 homeless people from crisis and long-term accommodation sites were surveyed using stratified, systematic sampling. The second stage involved a survey of a convenience sample of 100 homeless people from squats and the streets. Participants completed a questionnaire, Mantoux testing was performed and blood taken for gamma-interferon assay, liver and renal function tests. The group's health status was poor, with 72% experiencing medical conditions in the preceding two years and 77% symptoms in the month prior to interview. Bronchitis, asthma and gastroenteritis were the most commonly reported conditions; productive and persistent coughing, shortness of breath and wheezing the commonest symptoms. Twenty-one per cent had Mantoux reactions 15 mm or greater, 28% a raised GGT and 19% a raised ALT. Seventy-seven per cent smoked, 74% were current drinkers, 28% had injected drugs at some time in their lives and 14% were regularly injecting drugs. Forty-four per cent had experienced mental illness, 49% of whom reported depression and 15% schizophrenia. Homeless people in Melbourne have poor health status and engage in behaviours that place their health at risk. The high number of respiratory and gastro-intestinal complaints, the high level of cigarette smoking and injecting drug use (IDU) and the proportion likely to be infected with Mycobacterium tuberculosis (MTb) are all issues with important health consequences. Participants recruited from the street had significantly poorer health and engaged in more risk behaviours than those from accommodation sites; those from the accommodated sample were more likely to be infected with Mtb.