This dissertation analyses how the use of ruse is depicted in the Anglo-Norman chanson de geste 'Boeve de Haumtone', enlightened by selective comparisons with the 'Ystorya Bown de Hamtwn' - a very close adaptation in Middle Welsh - and further contemporary texts. It presents how literary representations throughout most ages and in various genres of medieval literature have reflected the morale ambiguity of ruse, while pointing out how its representation might participate of a paradigm shift from binary systems of oppositions toward tripartite complexes of contrasts, possibly characteristic of the literary production from 1200 onwards. Chapter 1 shows the specific relevance for this issue of 'Boeve', whose hero's journey will eventually lead to using devices of deception and treachery initially associated with his antagonists. Detailed attention is given to how the uses of ruse may be valorized differently, depending on the narrative instance judging its morality, underlining a dissonance between various characters' voices and the narrator. Chapter 2 closely examines the beginning of the text in that regard, while Chapter 3 systematises the different displays of ruse to be found in the first half of the poem. Chapter 4 shows how the two main female figures of the narrative are constructed in opposition to each other, using topological, biblical-like symbolism, strongly tied with their attitude toward deception. Chapter 5 expends on the structures of echoes, parallels and oppositions appearing throughout the whole of the text, illustrating how initially purely negative behaviours may be redeemed by careful consideration of their purpose, especially when ruse is utilized. The conclusion summarizes how, in that regard and in contrast of his antagonists, Boeve eventually manages to conciliate the use of ruse with the display of chivalric valour and bravery.