The heart rate strain of 14 Greek steelworkers was assessed during the winter and summer months of 1989 and 1990. Activity sampling was used to establish the pattern of work performed and heart rates were measured throughout work shifts. In addition, maximum aerobic capacity was estimated. The mean heart rate during work was 97 bt.min-1 (+/- 13), while the mean relative heart rate increase was 21% (+/- 15%). The results indicated that the work performed could be classified as light to moderate.