We study the impact of flavour in thermal leptogenesis, including the quantum oscillations of the asymmetries in lepton flavour space. In the Boltzmann equations we find different numerical factors and additional terms which can affect the results significantly. For degenerate light neutrinos, the upper bound on the CP asymmetry in a specific flavour is weaker than the bound on the sum. For hierarchical right-handed neutrinos—when flavour dynamics is included—there is no model-independent limit on the light neutrino mass scale, and the lower bound on the reheat temperature is relaxed by a factor of ∼(3–10).