Relationships between various measures of respiratory impairment and 10-year mortality from chronic respiratory diseases, cardiovascular disease and all causes have been investigated in 17,717 male London civil servants aged 40-64 years. Controlling for age and smoking habits, chronic phlegm production was significantly associated with all-causes and respiratory disease mortality. These associations did not persist after controlling for breathlessness or FEV1 percent predicted. Breathlessness was significantly associated with mortality from respiratory and cardiovascular diseases, and all causes. The associations persisted after controlling for age, smoking habits, employment grade, blood pressure, antihypertensive medication, plasma cholesterol level, diabetes, ECG changes, myocardial ischemia, and FEV1 percent predicted. Anti-hypertensive medication, myocardial ischemia and breathlessness showed the strongest associations with cardiovascular disease mortality. FEV1 less than 65% predicted was significantly associated with mortality from respiratory and cardiovascular diseases, and all causes; for the latter two, the rate ratios were not as high as those for breathlessness.