The purpose of the current study was to use a psychophysical methodology to establish acceptable impact severity levels for this automotive trim installation. Two studies were conducted. In the first study, 17 male and 12 female subjects (6 assembly line workers and 23 students) performed 5 hand impacts/min on a device that simulated the process of seating push pins during door trim panel installation. In both studies, subjects were asked to impact the simulation device as hard as they found acceptable without causing injury, numbness or pain. Subjects were trained for 11 h. Force and hand acceleration time-histories were recorded from the simulation device and a hand-mounted accelerometer, respectively. The magnitude of each impact was quantified with eight dependent measures: peak, time-to-peak, bad rate and impulse, from both the force and acceleration transducers. Statistics were used to determine the effects of gender, skill level and impact location on acceptable impact severity. In the second study, 8 male and 8 female subjects performed repeated hand impacts on a wall-mounted force plate at three different frequencies (2. 5 and 8 impacts/min) over three separate sessions. Force measures and statistics were the same as in Study 1. In the first study, impact Iocation did not appear to have a consistent effect on the acceptable impact severities and there was no significant differences observed between male and female values. For both force and acceleration, impulse was the most reliable variable followed by the peak. In the second study an increase in impact frequency was observed to result in a significant decrease in the acceptable levels ofpeak force and force impulse. This effect was largest when going from 2 to 5 impacts/min and was bess pronounced when going from 5 to 8 impacts/min (especially for force impulse). Male subjects demonstrated significantly higher acceptable impulse levels. Based on the combined results lrom both studies, acceptable limits were recommended for peak force and impulse that would be acceptable to 75% of the population for a range offrequencies. These bimits were observed to range from 181 (8/mm) to 259 N (2/mm) for peak force and 2.53 (8/mm) to 3.52 Ns (2/mm) for force impulse. lt was concluded that force impulse and peak force were the variables most likely being controlled by the subjects. Relevance to industry: Automotive assembly includes a number of tasks that involve hand impacts within the manufacturing process. One such task is the door trim panel installation process where the base of the hand is used to impact the door trim panel and drive fastening push pins through holes in the metal door frames. The current study provides tolerance limits so that industrial tasks involving hand impacts can be evaluated for their injury risk.