Despite the large number of instruments developed to assess the more purely cognitive executive functions in Brazilian children, few studies have developed instruments for the assessment of the most motivational components of these functions. The primary aim of this study was to develop a computerised version of the Children's Gambling Task (CGT) to assess affective decision-making in preschoolers. The present study also aimed to investigate whether this version of the task is sensitive to developmental changes across the preschool period and to examine gender differences in decision-making. We administered the CGT and the Columbia Mental Maturity Scale (CMMS) to 137 Brazilian children between the ages of three and five years old. Age differences between three-and four-year-olds, but not between four-and five-year-olds were found. Gender differences were not found. From this preliminary study, the computerised version of the CGT for Brazilian child population proved to be suitable for Brazilian child population.