A significant spectral change from solution to vacuum-deposited films was observed in a 2,3-dicyanopyrazine dye, 5-t-butyl-6-[4-(dibutylamino) styryl]-2,3dicyanopyrazine. In absorption spectra, a large hypsochromic shift was recognized. On the other hand, a large bathochromic shift occurred in fluorescence with considerable fluorescence quenching. The dye films were characterized as the single crystal phase, then estimation of exciton interaction was carried out on the basis of the crystal data. The result indicated that the electronic states of the dye films are considered to be similar to those of H-aggregates.