INTRODUCTION: The aim of this study was to provide additional evidence on the psychometric properties in the Portuguese population of three stigma scales: Mental Health Knowledge Schedule (MAKS), Scaling Community Attitudes Toward the Mentally Ill 12 (CAMI-12), and Reported and Intended Behaviour Scale (RIBS). METHODS: A total of 3556 participants were recruited and completed the three scales online. The study includes confirmatory factor analysis, internal consistency analysis, test-retest reliability, convergent validity, and known-groups validity tests. RESULTS: The results suggest that the European Portuguese RIBS version appears to be a valid measure of stigma in the Portuguese population, as well as the CAMI-12 "Prejudice and Exclusion" subscale and a modified version of MAKS. The results corroborate the existing evidence of a positive correlation between mental health-related stigma and low educational status, as well as reduced contact with someone with mental illness. CONCLUSION: The findings of this study contribute with additional evidence on the validity and reliability of the proposed European Portuguese versions of these three scales.