Although human immunodeficiency virus (HIV) clade C virus infects the largest populations worldwide, to date there are no prospective studies reported thus far to determine the incidence or prevalence of HIV dementia in this population. HIV clade C virus is a CCR5-tropic virus and thus predominantly infects macrophages, which are the key cells implicated in the pathogenesis of HIV dementia. However, HIV dementia has only rarely been reported in these populations. The authors thus used a recently developed International HIV Dementia Scale (IHDS) to screen a well-characterized cohort of HIV-infected discordant couples in Pune, India. 48 HIV+ subjects with CD4 cell count <200 cells/mm(3) and 48 HIV- subjects were studied. The HIV+ subjects had significantly lower IHDS scores compared to the HIV- subjects. 35% of the HIV+ subjects and 15% of the HIV- subjects scored < 10 on the IHDS. These observations suggest that the prevalence of HIV dementia may be higher in this population than previously reported. More importantly, it demonstrates that the IHDS can be used as a screening tool in the Indian population.