The aim of this study was to quantify physical work load of blue-collar workers and to compare the work load factors between aging (451) and young workers. The subjects included 63 men (41 construction workers and 22 vehicle inspectors). The dynamic (HR), static postural (OWAS) and perceived (RPE) work loads were assessed at work sires. HR and the number of poor work postures were similar when the aging and young subjects were compared in their occupational groups. During work, RPEs varied from "light" to "fairly hard" regardless of age or occupation. The differences in physical work load between the aging and young construction workers and vehicle inspectors were minor. The results suggest that the physical work load of blue-collar workers is not affected by age.