In order to study the effect of welding fumes on respiratory symptoms a cross sectional study was performed in 1982 among 2,660 welders, primarily shipyard welders, compared with a control group of 881 electricians. Only workers more than 34 years of age and in work at the time of the study were selected. Information about respiratory symptoms (using standardized BMRC questions) and exposure was obtained through a self-administered questionnaire. Seventy-four never-smoking welders and 31 never-smoking controls were selected for detailed clinical interviews and extended lung function tests. This article presents the results of the questionnaire study. The welders showed a significantly higher prevalence of chronic bronchitis: 21% versus 9% in the control group (p less than 0.01). The difference could neither be explained by differences in age or smoking habits nor by exposure to other air polluting substances. Other symptoms from the lower and upper respiratory system were also significantly increased among the welders. A dose-response relationship was found between exposure to welding fumes and the prevalence of symptoms from both the upper and lower respiratory system.