Work-related airways symptoms are common in woodworkers. To study possible work-related effects on lung function, 40 exposed woodworking teachers and 31 controls were examined by spirometry, diffusion-capacity and nitrogen-washout determinations, and methacholine challenge. Measured levels of total and respirable dust and terpene concentrations in the shops were below the Swedish threshold-limit values. Lung-function values on Monday morning were similar in the two groups. Slight obstructive impairments during the working week were found in both groups. In the woodworking teachers, small changes in lung function were related to measured total dust, use of process ventilation, and use of a broom to clean the benches. Their methacholine reactivity was slightly more pronounced compared with that of the controls, but the numbers of hyperreactive individuals (PC&inf20; < 8 mg/m(3)) were equal in the two groups. These facts might indicate small work-related effects on lung function, but some contradictory findings disturb this interpretation. The results are therefore inconclusive.