It is possible to divide the origin of the opera into two stages. The first one would be its birth on the courts of northern Italy at the end of the 16th century under the guise of stile rappresentativo. The second stage takes place in Venice in the late thirties, where its „public life“ began in the public theaters. It was there that opera started to develop the characteristics which would define it in the 17th and 18th centuries: the recitative began to be the place where the plot was developed and stirred, in comparison with the aria that was becomming a place of emotional reflection and expression. Claudio Monteverdi was a key person in this process. His opera Orfeo is a distinctive representation of court opera of the „first phase“, and his Il Ritorno d'Ulisse in Patria of the first operas written and performed in Venice. Since all the operas Monteverdi wrote in the thirty years that separate the two mentioned works are lost, the goal of this paper is to try to find traces of this path in Monteverdi's madrigals. The analysis of Orfeo, Il Ritorno d'Ulisse in Patria and a selection madrigals will show the differences in the compositional approach between the two operas, as well as the connections between them and the madrigals. This hypothesis makes it possible to assume that the madrigals written in the period between the two operas reflect the changes that were starting to happen in the composition of the operas.