Human operators are still a vital resource in modern manufacturing systems, especially for fine assembly tasks. Declining muscle strength due to physical tasks can impair psychomotor skills and can cause adverse effects on assembly quality. To understand how local muscle fatigue can influence multiple psychomotor skills, 20 subjects participated in an experiment in which four psychomotor tests were performed to mimic fine assembly tasks, and their performances under nonfatigued wrist and fatigued wrist conditions were compared. Results showed that wrist fatigue caused significant decrements in the dexterity of fingers and fingertips, but there was no significant influence on arm‐hand steadiness. Local muscle fatigue impairs psychomotor skills to different extents but does not necessarily lead to lower performance. Humans are capable of coordinating motion units to compensate for the influence of muscle fatigue, but this is rather limited. It is suggested that in assembly operations, tasks should be arranged according to different task demands on diverse psychomotor skills.