Portuguese Abstract: mercado acionario brasileiro vive em crescimento constante, porem ha conflitos de interesses entre o principal e o agente quanto a gestao dos recursos aplicados, que por sua vez originam o problema de agencia. Entao, a relacao entre esse cenario de conflitos e a complexidade e obscuridade do sistema tributario brasileiro esta diretamente relacionada ao investidor, uma vez que este busca o maior retorno possivel de seus investimentos. Desse modo, boas praticas de governanca tributaria para a reducao da carga tributaria incidente sobre o lucro das companhias, pode ser uma estrategia a ser utilizada pelas empresas para reduzir a taxa minima de retorno demandada pelos acionistas. Assim, esta pesquisa buscou analisar o efeito da Governanca Tributaria sobre o custo de capital proprio das empresas brasileiras listadas na B3. A amostra final resultou em um painel balanceado formado por 300 observacoes, cuja analise compreendeu 60 empresas no periodo de 2012 a 2016. Os dados analisados foram extraidos da Bloomberg® e do Formulario de Referencia disponivel no sitio eletronico do Brasil, Bolsa e Balcao (B3). A metodologia utilizada foi a regressao multipla do tipo pooled. Os resultados encontrados sugerem que as boas praticas de governanca tributaria influenciam, estatistica e positivamente, o custo de capital das empresas brasileiras, isto e, a medida que nao ha reducao dos fluxos de caixa provenientes do pagamento de tributos, os investidores aumentam a taxa de retorno esperada dos investimentos realizados. Concluindo, que a variacao no custo de capital proprio das empresas pode ser explicada pela adocao da governanca tributaria. English Abstract: The Brazilian stock market is constantly growing, however, there are conflicts of interest between the principal and the agent regarding the management of the funds invested, which in turn give rise to the agency problem. Thus, the relationship between this scenario of conflicts and the complexity and obscurity of the Brazilian tax system is directly related to the investor as he seeks the highest possible return on his investments. Thus, good tax governance practices to reduce the tax burden on companies' profits may be a strategy that companies can use to reduce the minimum rate of return demanded by shareholders. Thus, this research sought to analyze the effect of Tax Governance on the cost of equity of Brazilian companies listed in B3. The final sample resulted in a balanced panel composed of 300 observations, whose analysis comprised 60 companies in the period from 2012 to 2016. The data analyzed were extracted from Bloomberg® and the Reference Form available on the website Brazil, Bolsa e Balcao (B3). The methodology used was pooled multiple regression. The results suggest that good tax governance practices influence, statistically and positively, the cost of capital of Brazilian companies, that is to say, as there is no reduction of the cash flows from the payment of taxes, investors increase the rate of expected return on investments. In conclusion, the change in the cost of equity of companies can be explained by the adoption of tax governance.