The masking-level difference for a 500-Hz pure tone signal was examined for an interaurally in-phase noise having different degrees of power fluctuations. MLDs were reliably smaller in noise having relatively low power fluctuations. This effect was due to the following trends in the threshold data. (1) For all subjects, the So threshold improved as the degree of noise fluctuation decreased. (2) For some subjects, the Sπ threshold worsened as the degree of noise fluctuation decreased. (3) For some subjects, the Sπ threshold stayed constant as the degree of noise fluctuation decreased. These results are discussed in terms of comodulation masking release and the relevance of envelope cues for the MLD. [Work supported by AFOSR.]