A process for the manufacture of sustained release pellets comprising pelletizing a mixture containing the drug in finely divided form and a binder. The characteristic feature is that: (a) said binder is in particle form consisting of one or more water-insoluble wax-like binder substance(s) with a melting point above 40.degree. C., and (b) said pelletization step is performed by mechanically working said mixture, in a high shear mixer, under the input of a sufficient amount of energy for the binder to melt and pelletization to take place.