The aim of our study was to examine sex-specific associations between different aspects of socioeconomic status (SES) (educational level, occupational status, income) and lung function in a general adult population. In the Hordaland County Cohort Study, 1,644 subjects aged 26-82 yrs at baseline answered questionnaires and performed post-bronchodilator spirometry both in 1996-1997 and in 2003-2006. We performed adjusted linear regression analysis on the effect of SES on decline in forced experimental volume in 1 s (FEV(1)), forced vital capacity (FVC) and FEV(1)/FVC. Mean annual decline in FEV(1) from baseline to follow-up was 57 mL (se 1.3) and 48 mL (se 1.0) for males and females, respectively. Males had a larger decline in FVC than females, while females had a larger decline in FEV(1)/FVC. Lower education and low occupational status were associated with larger male lung function decline. SES did not affect female lung function decline. However, marital status was a significant predictor; unmarried females had less decline than both married and widowed females in both FEV(1) (adjusted mean annual difference 8 mL and 16 mL) and FVC (adjusted mean annual difference 8 mL and 18 mL). Low SES was associated with increased lung function decline in males. For females, marital status was more important.