The effects of computer system response time (slowvs. rapid) and method of pay (incentive vs. nonincentive) on mood disturbances and somatic discomfort were evaluated in a computer‐based data entry task among 45 professional typists. Self‐ratings of mood disturbances and somatic discomfort were taken at regular intervals over four consecutive workdays. Regardless of method of pay, slow response time generated higher ratings of frustration and impatience than did rapid response time. In addition, ratings of rush and tension were higher with incentive pay than without incentive pay, regardless of system response time. Mood disturbances and somatic discomfort increased linearly with the amount of time spent performing the data entry task over the course of the workday. This effect was independent of system response time or method of pay. However, scheduled rest and lunch breaks moderated these cumulative increases in mood disturbances and somatic discomfort. The results indicate that computer systems which incorporate features such as rapid response times reduce work stress, while the motivational advantages of computer‐based incentive pay programs must be balanced against the stress effects of this method of pay.