Cassava (Manihot esculenta Crantz) is the third-largest carbohydrate food source in the tropical region after rice and corn. Its flesh is consumed as food and food products, while other parts of the plant are yet to be fully exploited. This research aimed to evaluate the proximate composition of the cassava plant (Rayong 90 variety). Six different parts namely leaf, petiole, young stem, tuber, cortex and periderm of white variety cassava plants were dried and powdered to determine their proximate composition (protein, carbohydrate, fat, crude fibre, ash and moisture content). The results showed that leaf provided the most nutrients compared to other parts. Leaf had 43.80% carbohydrate, 23.87% protein, 13.66% crude fibre, 6.53% ash, 6.00 % crude fat and 5.00% moisture content. The crude protein for other parts was very low, ranging from 2.54% to 10.20%. The white cassava variety plant was very high in carbohydrates, ranging from 30.48% to 86.77% of dry matter. The mean percentage of crude fat was within the range from 0% to 6.00%. From the results, it can be concluded that the leaf of white cassava variety can be used to develop a high carbohydrate and protein ruminant feed as it has appreciable levels of nutrients.