In this paper, we present spectroscopy studies of poly (p-phenylene vinylene) p-doped by chemical or electrochemical ways with SO3- and BF4-, respectively. Since very few experimental data are available for in situ Raman studies of electrochemically doped samples, we have essentially used this technique in different resonance conditions (resonance Raman scattering (RRS)) to carry out our investigations using different excitation wavelengths. Several modifications in the Raman spectra of doped PPV compared to neutral PPV are analyzed and interpreted by the coexistence of polaronic and bipolaronic species in the sample. These results are illustrated in particular by gradual shifts in the frequency of carbon-carbon stretching vibrations, explained in terms of a quinoid character growing at the expense of the benzenoid one when the doping level is increased.