Nigeria has an estimated 930 000 AIDS orphans, which has a marked impact on family and community. This study was performed to characterise caregivers’ knowledge regarding HIV/AIDS and their attitude towards HIV/AIDS, orphans in general and AIDS orphans in particular. Caregivers and non-caregivers aged 25–70 years in Nigeria were interviewed from January and March 2003, and logistic regression analysis was used to determine associations between caregivers’ knowledge regarding HIV/AIDS and attitudes towards HIV/AIDS, orphans and AIDS orphans, and demographic characteristics and background status regarding HIV/AIDS and orphans. A total of 824 interviewees participated in the survey (82.4% response rate), of whom 290 (35.2%) were current caregivers of orphans. The mean number of orphans per current caregiver was 1.8 (standard deviation 1.4). Factors related to higher knowledge level regarding HIV/AIDS were female gender [odds ratio (OR) = 3.49; 95% confidence interval (CI): 2.33, 5.22] and belief that AIDS is a common disease (OR = 3.39; 95% CI: 2.19, 5.26). Factors associated with positive attitudes towards HIV/AIDS, orphans in general and AIDS orphans in particular were age 35–44 years (OR = 1.73; 95% CI: 1.11, 2.69), Koranic schooling (OR = 8.69; 95% CI: 2.42, 31.19), polygamy (OR = 1.76; 95% CI: 1.17, 2.62), belief that there are increasing numbers of orphans in the community (OR = 2.59; 95% CI: 1.32, 5.08) and having relatives or friends with HIV/AIDS (OR = 2.88; 95% CI: 1.61, 1.58). There was a slight correlation (r = 0.17, P < 0.001) between caregivers’ knowledge regarding HIV/AIDS and positive attitudes towards HIV/AIDS, orphans and AIDS orphans. Demographic characteristics and personal experience should be taken into consideration to improve attitudes and behaviour related to HIV/AIDS and caring for orphans and AIDS orphans.