In this letter, we report on the effect of stimulated Ramam scattering (SRS) on the hybrid wavelength-division-multiplexing (WDM) system. The stimulated Raman scattering-induced crosstalk was measured by using a two-channel hybrid WDM system and compared with the theoretically calculated values. Using this result, we estimated the maximum number of WDM digital channels that a hybrid WDM system could support.