ABSTRACT Purpose It is known that some autistic individuals are considered non-verbal, since they are unable to use verbal language and barely use gestures to compensate for the absence of speech. Therefore, these individuals’ ability to communicate may benefit from the use of the Picture Exchange Communication System – PECS. The objective of this study was to verify the most frequently used words in the implementation of PECS in autistic children, and on a complementary basis, to analyze the correlation between the frequency of these words and the rate of maladaptive behaviors. Methods This is a cross-sectional study. The sample was composed of 31 autistic children, twenty-five boys and six girls, aged between 5 and 10 years old. To identify the most frequently used words in the initial period of implementation of PECS, the Vocabulary Selection Worksheet was used. And to measure the rate of maladaptive behaviors, we applied the Autism Behavior Checklist (ABC). Results There was a significant prevalence of items in the category “food”, followed by “activities” and “beverages”. There was no correlation between the total amount of items identified by the families and the rate of maladaptive behaviors. Conclusion The categories of words most mentioned by the families could be identified, and it was confirmed that the level of maladaptive behaviors did not interfere directly in the preparation of the vocabulary selection worksheet for the children studied.