HIV-associated dementia (HAD) has received little attention in sub-Saharan Africa, and there are no data available from Malawi. We used the International HIV Dementia Scale (IHDS), a cross-cultural, simple and validated screening tool to study the prevalence of suspected HAD, defined as an IHDS score <or=10, in adult patients of a large urban antiretroviral (ART) clinic in Blantyre, Malawi. Use of the IHDS was feasible in our setting. The overall prevalence of suspected HAD was 14.0% (95% confidence interval 8.9-19.1%); there was no significant difference in prevalence between 134 patients on ART for at least six months and 45 patients not on ART (13.4% versus 15.6%; P = 0.722). Male gender and low education level were independent risk factors of suspected HAD. More knowledge of the value of the IHDS to predict ART outcomes is required.