Isotropic and Anisotropic Raman spectra of RNA and DNA solutions have been obtained with a scanning monochromator system. The registration of the spectra was optimized for the special purpose of extracting bandwidth information and the non-coincidence effect. The following polynucleotides were selected: poly(rA) poly(rU) , poly(rA) . poly(rU) , poly(rk-rU) . poly(rA-rU) , poly(dA) . poly(dT) and poly(dA-dT) .poly(dA-dT) . The spectra obtained were compared wi th those of rAMP and rUMP. Temperatures were varied for all systems. The transitions from stacked -to unstacked structure (single stranded polynucleotides) and from double stranded - to single stranded structure influence the vibratioral bandwidths. Dynamic behaviour of the adenine vibrations at 1334 and 1480 cm follows curves similar to those observed for the Raman hypochromc effect. The totally symmetric stretching vibration in adenine at 725 cm-1 however changes only weakly in bandwidth, while it shows a strong hypochromic effect. The bandwidth even at temperatures above the stacking/unstacking transition is much smaller than for rAMP. Other bandwidth changes will be discussed. The non-coincidence effect, measured as(?aniso -?iso) is shown to occur in vibrations originating in the aromatic base molecules. The1magnitude of the non-coincidence effect of the adenine vibration at 1505 cm-1 is different in poly(rA) and rAMP.