This dissertation aims to estimate the effects of maternity leave legislation in women´s wages and employment in Brazil. Therefore, we analyze the impacts of an increase in the leave period, which was raised from 12 weeks to 120 days, due to the Federal Constitution of 1998. The effect of the legislation is ambiguous a priori. One should expect that the leave would have negative effects to the extent that it raises the cost to the employers. On the other hand, the legislation can have positive effects if it avoids that women leave the labor market each time they have a child, thereat, increasing the firm-specific human capital of those workers. We utilize a simple difference in differences methodology with data form Pesquisa Mensal de Emprego between 1986 and 1991. The results show that the leave increase had no significant impact, which reinforces the conclusion that the maternity leave legislation does not impose higher costs to the employer. We also find no signs that the leave had raised women´s retention on the labor market, even in the case for the more educated female workers. The results also show insignificant impact in women´s employment.