Purpose Many perceptual processing processes, such as cognition, vision, sensation, and audition, are affected due to fatigue. Musicians are prone to fatigue because of long working hours and demanding profession. The research on assessing working memory abilities in musicians is heterogeneous, as none of the studies has controlled the effect of fatigue. This study was thus designed to assess the effect of fatigue on working memory and auditory perception in trained instrumental musicians. Method Twenty-six trained instrumental musicians and 25 nonmusicians participated in this study. The effect of fatigue was assessed by administering the working memory and auditory perception tests in prefatigue and postfatigue conditions. The fatigue was assessed using a 100-point visual analog scale. The working memory was assessed using Operation Span, Reading Span, and Digit Span (Forward and Backward) tests (Knutson et al., 1991). Auditory perception was assessed using speech-perception-in-noise and temporal integration tests. Results Working memory and speech perception were affected due to fatigue. Musicians, despite having better working memory abilities than nonmusicians, are equally prone to fatigue-related distress. Conclusion The advantage of music training for the working memory abilities may be reduced due to fatigue; hence, measures to reduce fatigue should be employed by the musicians. Fatigue should also be treated as a variable in all future research related to assess cognitive processing in musicians.