OBJECTIVE: To investigate the prevalence and sociodemographic risk factors for HIV infection, during the early stages of the epidemic, in a rural area of northern Malawi. METHODS: As part of a community-based study of mycobacteria, socioeconomic data and HIV results are available on approximately 30,000 individuals from random population samples in 1981-1984 and 1987-1989 from a rural area of Malawi. These have been analysed to characterize the early stages of the HIV epidemic. RESULTS: The earliest HIV-positive specimens were collected in 1982. HIV prevalence in individuals aged 15-49 years was 0.1% in the early 1980s and 2.0% in the late 1980s. In the early 1980s, eight out of 11 HIV-positive individuals were new immigrants to the district or had recently returned there. In the late 1980s, immigration and having spent time outside the district continued to be major risk factors for HIV. HIV infection was more common in those with occupations other than subsistence farming, in those with more schooling, and in those in the best housing. The association with schooling was seen at all ages for both men and women. CONCLUSION: Immigration and travel were important in the repeated introduction and establishment of the HIV epidemic. The association with schooling is similar to that found elsewhere in Africa.