In this paper, crosstalk induced by cross phase modulation (XPM) and stimulated Raman scattering (SRS) in a multiwavelength subcarrier multiplexed transmission system is analyzed. Then combined effect of SRS and XPM induced crosstalk in the system performance is investigated. It is found that SRS dominates at lower modulation frequency with large channel spacing while XPM at higher modulation frequency and lower channel spacing. BER performance is also mentioned in presence of SRS and XPM crosstalk for per wavelength channel capacity of 10 Gb/s. Maximum allowable power for a BER of 10-9 as a function of wavelength channel separation is also presented.