Abstract: In the first large scale community study of HTLV-1 prevalence in central Australia we found an adult prevalence of 36.8%, the highest reported worldwide. Prevalence increased with age suggesting that sexual contact may be the predominant mode of transmission. Although a wide range of HTLV-1 proviral loads was found, in nearly 40% of participants this exceeded 1000 copies per 105 peripheral blood leukocytes, a level that has been associated with an increased risk of chronic lung disease and death in this population. The median PVL for participants who were symptomatic with HTLV-1 associated inflammatory diseases was 1.34 log10 higher than that of those who were asymptomatic. These data demand a public health initiative to reduce HTLV-1 transmission among Aboriginal Australians.