Purpose To translate and adapt the assessment tool Language Use Inventory from English to Brazilian Portuguese. Methods The study was carried out in two stages. Once the publisher’s authorization was given, the process of translation and back-translation of the protocol was initiated, adapting it to sociocultural aspects, such as expressions, names, and adequate examples in Brazilian Portuguese. In order to investigate the internal reliability of the translation process, the Cronbach’s alpha coefficient was used. The second stage was a pilot study, in which the questionnaire was applied to 43 parents of children from 24 to 47 months old from a city in the State of São Paulo, Brazil. The results were analyzed according to the total score and to the subscales of the questionnaire. The variables age range and parental level of education were also analyzed. Results The analysis using the Cronbach’s alpha coefficient showed high internal consistency (α>0,98) in almost all the subscales which means that the instrument adapted to Brazilian Portuguese can be used. In the pilot study, an age effect was found in the total score and in the LUI subscale scores, i.e., the older the children, the fewer gestures they used, with more words and syntactic constructions. Conclusion The Brazilian-Portuguese version of the LUI questionnaire seems to be a reliable translation of the original and a reliable instrument to evaluate preschoolers’ language pragmatics. After future detailed analyses, it will allow early diagnosis and intervention in children with language disorders.