We have investigated the Raman phonons of several series of manganites: LaxMnyO3, La1-xCaxMnO3, RMnO3 (R = rare earth) with the (Pbmn) orthorhombic structure. Raman spectra of non-doped samples, RMnO3, correspond quite well with group theory analysis predictions but present anomalies in the width and intensity of several modes. The spectra of Ca-doped and non-stoichiometric samples are explained taking into account structural effects (both the disorder induced by doping and the reduction of the mean orthorhombic distortion) and the coupling of the phonons to the more or less delocalized e(g) electrons, related to polarons. (C) 1999 Elsevier Science B.V. All rights reserved.