•The Psychosomatic Questionnaire for Children and Adolescents was easily understood.•The Psychosomatic Questionnaire for Children and Adolescents had good reliability and validity.•The Psychosomatic Questionnaire for Children and Adolescents can be used with Brazilian-Portuguese speaking children and adolescents with musculoskeletal pain. Psychosomatic symptoms seem to influence both the onset and development of pain. There is lack of Brazilian-Portuguese questionnaires that measure psychosomatic symptoms in children and adolescents. To translate and cross-culturally adapt the Psychosomatic Questionnaire for Children and Adolescents into Brazilian-Portuguese and English and test the measurement properties of the Brazilian-Portuguese version. The translation and cross-cultural adaptation (from Dutch to Brazilian-Portuguese and English) followed six steps. Interviews were conducted in 33 Brazilian children and adolescents. We also recruited 107 children and adolescents with musculoskeletal pain from schools to test the measurement properties of the Brazilian-Portuguese version. The questionnaire was completed twice with a 7-day interval. Ceiling and floor effects, missing data, internal consistency, reliability, measurement error and construct validity were assessed. We recruited 140 children and adolescents from public and private schools. During the cross-cultural adaptation process, no major difficulty answering and understanding the questionnaire were reported by children and adolescents. The questionnaire did not show ceiling or floor effects and had minimal missing data (0.37%). Internal consistency by the Cronbach's Alpha was 0.69. Test-retest reliability by the Intraclass Correlation Coefficient was 0.75 (95% CI: 0.64, 0.84). The smallest detectable change was 6.5 points out of 18 points. We observed a moderate correlation of 0.54 (p<0.01) with the Spence Children's Anxiety Scale, consistent with our a-priori hypothesis. The Brazilian-Portuguese version of the Psychosomatic Questionnaire for Children and Adolescents has acceptable measurement properties and is a good option for assessing psychosomatic symptoms in clinical practice and research.