Ready-to-drink fruit juices represent a large share of the market and are an important target for product development. The mixture of fruits can bring about improvements to nutritional and sensory aspects of these beverages while making used of the wide variety of exotic fruits from the Amazon region. Therefore, it is necessary to select mixed fruits and determine their ideal sweetness according to consumer acceptance. Consumers in the city of Belém (Brazil) evaluated five different concentrations of sugar using the just-about-right scale in two blends selected by preference ranking. For the cupuassu-acerola-açai blend, the optimum concentration of sugar was 9.5 g/100 mL, and for the soursop-camucamu-yellow mombin blend, it was 10.7 g/100 mL.