This dissertation explores how representations of gender in Os Lusíadas are paramount to understanding the poem, as they express contemporary concerns about the Portuguese nation and its empire. Masculinity and femininity play a crucial role, both at the historical and the mythological level in the definition of Portuguese identity during a time of crisis. Reading with an eye for gender showcases the many ambivalences in the poem and identifies those instances in which the dominant discourse about the nation and the empire is under stress, due to anxieties about the changes taking place in the Portuguese patriarchy. I consider particularly the representations of gender that emerge from the text and question heroic masculinity. Moreover, there are several "others" that are significant, such as women, non-Western men and mythological figures, who challenge, subvert and question Portuguese masculinity. Through a close reading of the epic poem I demonstrate how the poet's adaptation of Classical mythology and its fusion with history reveals the anxieties and ambiguities of the imperial context. I argue that women and mythological figures allegorize issues such as sexuality and marriage and communicate an important message to D. Sebastião, the dedicatee of the poem, who fails in his role as a father to the nation, and by extension, corrupts his masculinity. Moreover, Camões expresses his anxiety about the continuation of Portuguese heroic glory (kleos) and reveals that masculinity is threatened by the crumbling empire.