Abstract The colour of red onions is due primarily to anthocyanins present in the epidermal cells of the scale leaves of the bulb. The occurrence of the four major anthocyanins, cyanidin 3-glucoside, cyanidin 3-laminaribioside, cyanidin 3-malonylglucoside and cyanidin 3-malonyllaminaribioside, was confirmed in four red onion cultivars, namely ‘Mambo’, ‘Red Jumbo’, ‘Red Bone’, and ‘Red Granex’. In addition, four new minor anthocyanin pigments were isolated and characterized from red onions. Two structures were determined by chemical and spectroscopic methods to be peonidin 3-glucoside, and peonidin 3-malonylglucoside. This is the first report of the occurrence of simple and malonylated peonidin glucosides in red onions.