The use of doped p-terphenyl crystals as organic charge-transfer agents calls for detailed information on their structure. We report results on lattice (60-150 cm(-1)), torsional (228-230 cm(-1)), inter-ring (1250-1300 cm(-1)) and intra-ring C-C (1570-1630 cm(-1)) Raman-modes of p-terphenyl in doped crystals with tetracene and terrylene in order to compare them with those of the pure p-terphenyl crystal, looking for possible doping effects upon molecular conformational changes in the crystal, which greatly influence the excitonic properties. From the studied Raman spectra, we come to the conclusion that within the doping concentrations under study (less than 0.01%), at corresponding temperatures, there are not any significant spectral changes either in frequencies or in linewidths of the p-terphenyl Raman spectrum from the pure crystalline compound to the doped p-terphenyl/tetracene and p-terphenyl/tenylene doped crystals. The conformational changes in the doped-crystals induced with decreasing temperature seem to be the same as in the undoped crystal, including a non-discontinuous order-disorder phase transition at the same temperature.