Forty-five Northern Thai children with HIV infection or AIDS were examined for oral manifestations. Of these children, 51.1% (n=23) were asymptomatic (category N), 48.9% were mildly, moderately or severely symptomatic (category A, B, C) and 48.9% (n=22) revealed oral lesions. Eleven patients (24.4%) showed one oral lesion, eight (17.8%) had two and three (6.6%) had three oral lesions. Erythematous candidiasis was the most common lesion (17.8%). Oral hairy leukoplakia was seen in 6.7% (n=3). Geographic tongue, not usually considered to be associated with HIV infection, was seen in 6.7% (n=3). Only 15 patients (33.3%) received antiretroviral therapy (ART). Comparison of patients with or without ART did not show differences in the prevalence of oral lesions. More studies in Thai HIV-infected children are needed to reveal the prevalence of oral manifestations, as well as for the predictive value of the most common or specific oral manifestations.