Sweetness, sourness and fruitiness of 18 orange-flavored solutions, with three levels of citric acid (0.75, 1.5, 2.25 g/1) and three equi-sweet levels of either sucrose (80, 100, 120 g/l) or aspartame (0.6, 0.7, 0.8 g/l), were evaluated by time–intensity methodology. At these concentrations, a larger range in sourness intensity than in sweetness was produced, resulting in greater suppression of sweetness by increasing acid levels than of sourness by increasing sweetener levels. Although aspartame samples had a longer duration of sweetness and fruitiness, sucrose and aspartame did not interact differently with the sourness of citric acid. Fruitiness intensity and duration was enhanced by both sweetness and sourness, but to a greater extent by sourness. Whether this enhancement is attributable to a cognitive association of sweetness or sourness with fruitiness or is due to the inability of the subjects to separate sweet and sour tastes from orally perceived fruity flavor cannot be concluded from this study.