Routine investigation of the pigments of mural paintings from the Roman period generally yield a small number of pigment types. With the joint application of several analytical techniques (x-ray diffraction, optical emission spectroscopy, x-ray fluorescence) it was possible to distinguish the pigments of similar type from a multi-period painted Roman villa. Based on the determination of additives and trace elements, the seven red and six green samples analyzed could be grouped into five and six units respectively. Such an accurate characterization of the pigments, coupled with the data obtained from analysis of the levelling plaster, can help in separating the fragments recovered during excavation and in the elaboration of a relative chronology of the painted layers.