A case study was conducted using an automatic sphygmomanometer to compare the stress encountered by workers using two different machine actuation/safety devices. The experiment took place in a small metal stamping plant as part of a government authorized comparison of the devices. Six experienced female workers separately performed the same task on the same power presses using either a photo electronic or a two-hand button device. These two devices perform dual duty as both machine actuators and machine safeguards. Blood pressure at the ankle and heart rate were measured periodically and a questionnaire was administered. The case study approach to this experiment was necessitated by government restrictions which limit the population of workers experienced with both devices. The results of the case study are twofold: (1) For the small population tested no significant difference was found in the stress measures examined for machine operators; and (2) A feasible in-plant methodology is demonstrated for unobtrusively monitoring worker populations exposed to machine related stress.