We investigated the influence of repeated exposure to orangeades with added sucrose and different concentrations of citric acid, on the taste preferences of 6- to-11-year-old children and young adults. During an intervention study of 8 days, 59 children (9.2+/-0.9 years) and 46 young adults (22+/-2.0 years) received, each day, either an orangeade with a sweet taste, a sour taste, or no orangeade (control). Before (baseline) and after the intervention, preferences for a series of orangeades and yoghurt, which varied in balance of sweet and sour tastes, were measured by means of a rank-ordering procedure. The variation in balance of sweet and sour taste was established by adding different amounts of citric acid (orangeade: 0.009, 0.013, 0.020, 0.029, 0.043, and 0.065 M added citric acid; yoghurt: 0.027, 0.038, 0.056, 0.081, 0.12, and 0.17 M added citric acid) to a stock orangeade and yoghurt with 0.42 M sucrose. The sweet and sour tasting orangeade that were consumed during the intervention were equally preferred at baseline. After an 8-day exposure to the sweet orangeade, children's preferences for this orangeade (0.42 M sucrose) significantly increased (p<0.05). A similar trend was observed for the yoghurt with 0.42 M sucrose (p=0.09). An 8-day exposure to the sour orangeade did not have a significant effect on children's preference for this orangeade. The taste preferences of adults did not change after the intervention. The control group of children and adults did not show any change in preferences for sweet and sour tastes. Future research is needed to investigate whether the changed preferences for sweet taste are stable over time and how these changed taste preferences are related to a change in the consumption of sugar rich foods.