Self-pacing or avoidance of physiological strain by adjustment of work rate may be an important protective behaviour for manual workers in severe thermal conditions. Data were gathered at a number of industrial sites in the United Arab Emirates to assess whether self-pacing takes place in these workers. Heart rate and aural temperature were monitored in 150 subjects for 12 h daily over 2 consecutive days. Environmental parameters were measured for quantification of heat stress by the thermal work limit. There was no evidence of an effect of variation in environmental thermal stress on either average working heart rate or aural temperature. These studies provide evidence that self-pacing is a protective response to working in heat which does not require a highly informed workforce; recognition of this should form part of a holistic approach to management of heat stress in hot climates.