BACKGROUND: Increased arterial stiffness predicts future cardiovascular disease and in some cross-sectional studies it is related to worse lung function and obstructive pulmonary disease. We assessed the predictive value of lung function measured in mid-life as compared with later life on arterial stiffness in the Caerphilly Prospective Study (CaPS). METHODS: Men aged 47-67 years had lung function measured between 1984 and 1988 and repeated between 2002 and 2004 (n = 827) as well as having carotid-femoral pulse wave velocity (PWV) measured. RESULTS: Both forced expiratory volume in 1 s (FEV(1)) and forced vital capacity (FVC) in mid-life and later life were inversely associated with PWV (P < 0.0001) but mid-life measures were stronger predictors. Only mid-life measures remained predictors after mutual adjustment (FEV(1) mid-life beta coeff. -0.65, 95% CI -1.04, -0.26, P < 0.0001; FVC mid-life beta coeff. -0.52, 95% CI -0.82, -0.23, P < 0.0001). Adjustment for smoking status, early life, inflammatory and metabolic factors in sub-groups did not markedly change the associations. CONCLUSIONS: Mid-life lung function is a stronger risk factor than in later life for arterial stiffness in men. It is possible that developmental factors influence both lung function and arterial stiffness. Lung function assessment in mid-life may identify individuals at greater risk of their future cardiovascular disease.