The goal of the present research programme was to find out how common driver fatigue is among New Zealand truck drivers and the degree to which they suffer from fatigue-related effects on their driving performance. To that end, 606 truck drivers were tested at a variety of sites throughout the North Island of New Zealand. The results showed that a considerable number of drivers are operating in excess of the hours of service regulations. The three fatigue measures in our survey indicated that there are significant levels of fatigue in the New Zealand transport industry. One out of four of the drivers' self-ratings of fatigue were in the "tired" range, even though many of them were surveyed at the beginning of their shift. A psychomotor test also indicated a very high level of fatigue in the sample. Overall, 24% of the sample failed the psychomotor performance criteria. Amount of rest and sleep, shift length, and number of driving days per week were all significantly related to psychomotor performance. The results of the daytime sleepiness inventory showed that the drivers in our sample had somewhat higher levels of daytime sleepiness than do heavy goods vehicle drivers in Great Britain. There was significant correspondence between drivers' self-ratings, psychomotor performance, and daytime sleepiness fatigue measures.