The bioactive constituents and antioxidant activities of raw, fried and decoctions of cocoyam (Colocasia esculenta) tubers were investigated. The raw form contained considerable amounts of proximates, phytochemicals, minerals, vitamins, amylose, amylopectin and antioxidants (determined from carotenoid, reducing power and 2,2 diphenyl-1-picryl hydrazyl (DPPH) radical scavenging assays). Boiling of C. esculenta resulted in increases (p<0.05) in moisture, carbohydrates, tannins and amylose; significant decreases of fat, ash, protein, carotenoids, thiamine, amylopectin, reducing sugars and DPPH-scavenging activity; insignificant decreases of flavonoids, alkaloids, riboflavin, crude fibre and reducing power. Frying resulted in significant increases in fat, ash, carbohydrate, tannins and amylose; an insignificant increase in crude fibre; an insignificant decrease in riboflavin; but significant (p<0.05) losses of moisture, protein, ash, flavonoids, alkaloids, carotenoids, thiamine, amylopectin, reducing sugars, DPPH-scavenging activity and reducing power. The decreased reducing sugar and increased crude fibre and amylose contents following frying of C. esculenta could be of benefit to diabetics.