The present study aimed to assess the proximate chemical compositions of 16 rice varieties collected from Battambang, Takeo, and Prey Veng provinces in Cambodia. Proximate chemical compositions including moisture content, protein, total carbohydrates, fiber, ash, lipids, and amylose content were subjected to analysis. The results showed that all chemical compositions of the 16 rice varieties varied significantly (p <0.05). The carbohydrates and proteins were the main compositions in rice grain, ranging from 79 to 84% w/w, and 6 to 9% w/w, respectively. Moisture contents were reported from 6 to 12% w/w, while the fat contents were in the range of 0.1 to 0.5% w/w. For the minor composition, fiber and ash contents varied from 0.2 to 5% w/w, and 0.2 to 0.6 % w/w, respectively. The amylose content in the samples varied from 22 to 39%. Among the 16 collected rice varieties, the cultivated variety. ‘Srov Atung’ showed the lowest value of moisture content (6.7%) but it contained the highest value of carbohydrates (84.1%) and fat content (0.5%). The cv. ‘Krohorm Tgon’ showed the highest value of protein (8.05%) while the cv. ‘Phka Romdoul Takeo’ had the highest content of crude fiber (3.58%). The highest energy content (374.50 ± 2.03 Kcal/100g) was found in cv. ‘Srov Atung’, whereas, cv. ‘Neang Minh’ contained the least amount of energy (350.22 ± 3.85 Kcal/100g). In addition, cv. ‘Srov Vear’ contained the highest percentage of amylose (39.15%) and the lowest value was found in cv. ‘IR66’ (22.14%). Overall, the current study revealed the variation of chemical composition of rice grain from one variety to variety. The findings of this study could be used as database of local rice varieties and help the food processors to select suitable rice varieties for food product development, particularly for rice-based products.