The chemical composition, including the Proximal composition, cyanide and amino acid concentrations of leaves and root tissues, as well as the starch and sugar concentrations of root peel and parenchyma, of low-(M Col 113), intermediate-(M Col 22 and the hybrid CM 342-170) and high-(M Col 1684) cyanide-containing cassava cultivars at four plant ages (6, 8, 10 and 12 months) is presented. The local cultivar (M Col 113) showed lower leaf and root parenchyma dry matter contents, lower crude fiber and crude protein levels in root peel, a higher sugar content and lower cyanide concentration in root tissues, than the other three cultivars (M Col 22, CM 342-170 and M Col 1684). Most of the parameters studied were affected by the cultivar as well as by plant age. Less variability was observed for all criteria in the root parenchyma than in the leaves and root peel. The sulfur-containing amino acids were low in all tissues analyzed and a high concentration of arginine was found in the root tissue samples. The cyanide concentration of root parenchyma was less variable than that of leaves and root peel; the cultivar M Col 1684 showed a higher cyanide concentration in the parenchyma (900 to 1000 mg/kg DM) than the other three cultivars, which ranged from 100 to 200 mg/kg DM. The local cultivar (M Col 113) was the only one in which the cyanide concentration in leaves was higher than that of the root peel. The hybrid CM 342-170 produced roots with the highest dry matter and starch concentrations.