The relationship between traffic noise exposure and psychological morbidity was assessed using the population-based Caerphilly Collaborative Survey of 2398 men from Caerphilly, South Wales. The findings showed that traffic noise exposure levels were strongly associated with annoyance to noise. Noise-sensitive men were more likely to be highly annoyed by noise exposure than less noise-sensitive men. There was no direct association between noise exposure level and psychological morbidity but there were provocative interactions with noise sensitivity. The role of noise sensitivity is discussed as an indicator of vulnerability to environmental stressors and a measure of negative affectivity and over-reporting.