Cactus pear fruit could contribute to food security and human health. Cactus pear cultivars have different coloured fruit that may indicate the presence of different antioxidants. The aim of this investigation was to find a relationship between the fruit colour and the antioxidant content and capacity in the fruit from eight different cultivars representing the four colours of cactus pears available in South Africa. Antioxidant content analysis included betalains (spectrophotometric method) ascorbic acid (2, 6 dichlorophenol-indophenol titration), total phenolics (gallic acid/g) and carotenoids (hexane/acetone/ethanol, spectrophotometric method). DPPH (2, 2-dipehyl-1-picrylhydrazyl radical) and chelating activity of ferrous irons tests were done to determine antioxidant capacity. It was found that purple (O. robusta ‘Robusta’) and orange (O. ficus-indica ‘Gymno-Carpo’and O. ficus-indica ‘Ofer’) had the best antioxidant levels and capacity. Cactus pear fruit had extremely high capacity to chelate ferrous ions and high radical scavenging capabilities. It was found that betalains (betacyanins and betaxanthins) group with carotene in purple fruit, while ascorbic acid, phenolics and carotene group in orange fruit. Thus the fruit seems to have value as a health promoting sustainable crop with nutraceutical properties.