The effects of fatigue during a task involving prolonged repetitive light work were checked electromyographically and by rating the perceived musculoskeletal discomfort in seven different body regions. For a period of 120 min, 13 healthy female workers performed a repetitive light work task, simulating assembly work in electronics factories. The muscular activity levels were rather low, e.g., the median electromyographic (EMG) amplitude level during the work was 3-6% of maximal EMG amplitude level in the right trapezius muscle. According to the perceived musculoskeletal discomfort during the work task, the subjects were divided into a "most-complaining group" and a "least-complaining group." During the work task, a significant increase in the median EMG amplitude level of the right trapezius muscle was observed in the least-complaing group but not in the most-complaining group. The analysis of EMG signals revealed no definite signs of muscular fatigue during the work task in either of the two subgroups.