Nowadays, accessibility is a crucial factor for Web site development and use, and yet, people with visual disabilities face many accessibility barriers that hinder the adequate understanding of Web contents. In Brazil, the Federal Government published a law that formalizes the mandatory accessibility to Governmental Web sites’ content. In this context, it is necessary to define ways to evaluate accessibility to guarantee the quality of these sites in this respect. Therefore, this article proposes a means of Web accessibility evaluation through metrics. Author Keywords Web accessibility, Metrics. ACM Classification Keywords K.5.2 [Legal Aspects of Computing]: Governmental Issues – Regulation; K.4.2 [Computers and Society]: Social Issues; D.2.8 [Metrics].