In the past, the temporal resolution of the auditory system has been investigated using gap detection and temporal modulation transfer functions for nonspeech stimuli. The present study investigated temporal resolution by examining the effect of temporal smearing of the speech envelope on speech intelligibility. The envelopes of CVC nonsense syllables were calculated and convolved with a Gaussian temporal window that had different time constants. The original speech envelopes were replaced by the convolved ones which had poorer temporal resolution. Fifty non-sense syllables were processed in this way using a range of time constants. For each time constant, 50 processed CVC syllables were presented in random order to subjects. The temporal resolution of the speech envelope had a significant effect on subjects' recognition scores. The poorer the temporal resolution, the lower the recognition scores. The possible implications for the effect of temporal resolution on speech intelligibility will be discussed.