ABSTRACT: Human cassava toxicities have been attributed to cyanide in cassava. In this work, the effects of scopoletin (a coumarin compound present in cassava) and cyanide separately and in combination on protein, glucose-6-phosphatase and glutathione S-transferase activities of rat liver microsomes were compared. Four groups of male Wistar rats were fed rations containing 0.7μg scopoletin, 0.7μg scopoletin + 18mg cyanide and 18mg cyanide/kg feed respectively plus control group (without scopoletin or cyanide) for 12 months. The results showed a significant decrease (p < 0.05) in relative microsomal protein content, mg/g liver weight, of the scopoletin fed group relative to other groups. There was also a significant decrease (p < 0.05) of the glucose-6-phosphatase activity of the scopoletin and cyanide fed groups, while the cyanide fed group also showed a significant increase (p < 0.05) in glutathione S-transferase activity.