Dental caries is one of the most common chronic diseases among preschool children in Thailand. The aim of this study was to investigate the factors associated with caries experience in the underserved Hill Tribe preschool children in Doi Tung Development Project, Chiang Rai. One hundred Hill Tribe preschool children aged 3 to 5 years old were invited to participate in the study. The children were examined for decayed, missing, and filled teeth (dmft) and simplified oral hygiene index (OHI-S). The primary caregivers of the children were interviewed with the structured questionnaire regarding their family demographics and socioeconomic background, the 24-hour dietary recall food record and the oral health habits of the children. The relationships between caries experience (dmft) and gender, initial age of toothbrushing, assisted toothbrushing, OHI-S, daily carbohydrate snacking, sugary drinks at bedtime, dental visit experience, caregiver education level, and caregiver employment were studied using a multiple linear regression method. Statistical significance was set at p<0.05. The prevalence of dental caries among the Hill Tribe preschool children was 84 %. The mean dmft score was 5.8±5.0. The prevalence of dental caries had a significant relationship with daily carbohydrate snacking >2 times and dental visit experience. The multiple linear regression analysis revealed that dmft was significantly associated with OHI-S ≥1 (p=0.002) and dental visit experience (p=0.002). Dental caries were highly prevalent among the Hill Tribe preschool children. Reported consumption of carbohydrate snacks and dental visit experience were related with the prevalence of dental caries, and caries experience was associated with oral hygiene and history of dental visit experience.