BACKGROUND: There is a lack of valid and specific tools to measure chronic constipation severity in Brazil. AIMS: To validate the Constipation Scoring System for Brazilian spoken Portuguese. METHODS: Translation, cultural adaptation, and validation itself (reliability and convergent and divergent validation). Translation: definitive version from the original version’s translation and evaluation by specialists. Cultural adaptation: score content analysis of the definitive version, as an interview to patients. Interobserver reliability: application by two researchers on the same day. Intraobserver reliability: same researcher at different times, in a 7-day interval. Divergent validation: non-constipated volunteers. Convergent validation: two groups, good response to clinical treatment and refractory to treatment. RESULTS: Cultural adaptation: 81 patients, 89% female, with mean age of 55 and seven years of schooling, and overall content validity index was 96.5%. Inter and intraobserver reliability analysis: 60 patients, 86.7% female, mean age of 56 and six years of schooling, and the respective intraclass correlation coefficients were 0.991 and 0.987, p<0.001. Divergent validation: 40 volunteers, 25 male, mean age of 49 years, and the mean global score was 2. Convergent validation of patients with good response to clinical treatment: 47 patients, 39 female, mean age of 60 and six years of schooling, and the pre- and post-treatment scores were 19 and 8, respectively (p<0.001). Convergent validation of refractory to clinical treatment patients: 75 patients, 70 female, mean age of 53 and seven years of schooling, and the global average score was 22. CONCLUSIONS: The Constipation Scoring System (Índice de Gravidade da Constipação Intestinal) validated for the Brazilian population is a reliable instrument for measuring the severity of intestinal chronic constipation.