In this talk I will report on some precision test of the AdS/CFT correspondence in the sector of scaling dimensions of local Wilson operators in maximally supersymmetric Yang-Mills theory. After a brief introduction to the Bethe ansatz approach to the spectral problem I will explain how to solve the relevant equations in two limits of interest, the small and large spin limit. I will then discuss the weak to strong coupling transition and demonstrate the agreement with the string theory predictions at strong coupling.