A serosurvey was carried out to assess the prevalence of HIV infection in The Gambia and the importance of possible risk factors. The overall prevalence of HIV-2 infection among the 4228 adults studied was 1.7% while that of HIV-1 was 0.1%. The prevalence of HIV-2 was similar in both sexes but higher among those greater than 25 years of age and those who lived in two small towns along a main transport route. Among men, multivariate analysis showed prevalence of HIV-2 infection was significantly greater among those in the more affluent occupations, those without a secondary education and those with a history of urethral discharge. Among women, infection was more frequent in divorcees and widows and those who had been married several times. The prevalence was also higher in individuals born in Guinea-Bissau and in an ethnic group which originated there.Researchers took blood samples from 4228 adults aged 15 years in The Gambia to determine the prevalence of HIV-2 infection and risk factors. HIV-2 infection was more prevalent than HIV-1 infection. HIV-2 prevalence stood at 39% for females and 31% for males, but the difference was insignificant. Individuals 25 years old were more likely to be HIV-2 seropositive than those 25 (p.01). Further, HIV-2 prevalence was significantly higher in the small towns of Soma and Farafenni on the Trans-Gambia Highway than other areas of the country (p.01; 3.2% vs. 1.3% for Greater Banjul and 1.4% for the remainder of the country). It also was greater for people who had their blood samples taken at a health center than those who gave theirs elsewhere (p.01). HIV-2 infection was more prevalent for people born in Guinea- Bissau and in the Manjago tribe which originated from Guinea-Bissau than those born in The Gambia or elsewhere (p.025 for place of birth and p.01 for tribe). Marital status played an insignificant role in seropositivity for men, but divorced and widowed women had a significantly greater infection rate than other women (p.001; odds ratio [OR] 10.4 vs. 1-20). Further, infection significantly increased as the number of husbands women had had increased (p.05; OR 6.8). HIV- 2 positivity was significantly higher among women who reported using a condom at least once during the past year with casual partners (p.01; OR 16.7). Skilled manual laborers, businessmen, and traders were more likely to be infected with HIV-2 than farmers, unskilled laborers, and while collar men (p.05). Men with at least a secondary education were at significantly lower risk than men with less than a secondary education (p.01; OR .1 VS. .7-1.6). Men who had had at least 2 cases of urethral discharge had a significantly higher infection rate than those who did not (p.005; OR 4.8 vs. .8-1).