A methodology is presented for the 'on-site' evaluation of work-related physical activities. In a first session, video recordings were made of six industrial plant workers during their routine occupational tasks. Heart rate (HR) and subjective perception of effort were monitored. The video recordings were then analysed with appropriate software to determine the musculo-skeletal load ('Vision 3000', Promatek, Montreal) and to evaluate energy expenditure ('Energy', University of Michigan). The indirect estimates of energy expenditure were validated in a second session by monitoring the six subjects' oxygen consumption (VO2) during the same activities with a portable telemetric oxygen uptake analyser (Cosmed 'K2', Rome). No statistically significant differences were found between direct measurements of VO2 and the computerised estimates of energy expenditure. Biomechanical parameters obtained in the two sessions did not differ. Therefore, we conclude that the 'Energy' programme and the 'Vision 3000' program provide a fast and reliable profile of job requirements.