Khanam, U. K. S. and Oba, S. 2013. Bioactive substances in leaves of two amaranth species, Amaranthus tricolor and A. hypochondriacus. Can. J. Plant Sci. 93: 47-58. Bioactive substances and phenolic contents of Amaranthus tricolor and A. hypochondriacus leaves were evaluated using four cultivars of each species. Leaf colour attributes (L*, a* and b*) and betacyanins varied widely among the cultivars. The a* value, betacyanins and betaxanthins, appeared to be rich in A. tricolor, whereas betxanthins were twofold higher in A. hypochondriacus. Isoqercetin and rutin were the most abundant flavonoids in all amaranth cultivars. Hyperoside was found only in the A. hypochondriacus cultivar New Aztec. Salicylic acid, syringic acid, gallic acid, vanilic acid, ferulic acid, p-coumaric acid and sinapic acid were the most common phenolic acids in all amaranth cultivars. Significant amounts of ellagic acid and sinapic acid were detected in A. hypochondriacus cultivars. Total phenol content (TPC) was found to be strikingly greater than total phenol index (TPI) in A. tricolor than in A. hypochondriacus. All the amaranth cultivars showed a high correlation between total antioxidant activity and total phenol content.