Sensitivity permitting, natural abundance 13 C offers a much better spectral resolution than proton NMR. This is due to an important chemical shift range and to proton decoupling conditions which yield one peak per carbon with practically no overlap. However, PGSE experiments, which lead to the diffusion coefficient associated with each peak, have scarcely been employed. In this paper, we present and compare different ways to access this quantity and we have effectively verified that, without any precaution, diffusion coefficients cannot be properly determined from standard procedures. The cause of such a failure is decoupling during the gradient pulses. We have used a very simple remedy which proved to be very successful on a model mixture of three monoterpenes and which appears as being of general applicability. 2 Introduction: