Investigation of the chemical composition of the water soluble fraction of the methanolic extract of the roots of Eurycoma longifolia, a medicinal plant popularly known as "Tongkat Ali", afforded three quassinoid diterpenoids, sugar and amino acid fractions. The sugar fraction was analyzed for its qualitative and quantitative carbohydrate con tent and glucose and fructose were identified. Quantification of these natural free sugars was achieved by HPLC using refractive index detection. The total amino acid concentration and the amino acid pattern, i.e., the relative proportion of each amino acid to the total amino acids, in the amino acid fraction were analyzed using an amino acid analyzer. Twenty five amino acids were identified. The predominant amino acids were alanine, proline, arginine, and serine summing up to 53.39% of the total. The isolated quassinoid diterpenes exhibited potent cytotoxicity and antimalarial activity.