Crop farming as a risk factor for respiratory symptoms of obstructive lung disease was assessed. Random samples of crop farmers from four European countries were studied following a cross-sectional design. A questionnaire on respiratory symptoms and occupation was administered to determine prevalences, and the roles of the various crops as risk factors for respiratory symptoms were assessed through logistic regression modeling. The 4,793 crop farmers included in the study (response rate: 85.3%) reported the following respiratory symptoms: wheezing (14.9%), asthma (3.3%), nasal allergy (14.4%), chronic phlegm (12.4%), organic dust toxic syndrome (ODTS) (15.2%), and symptoms at work (22.0%). In the multivariate analysis, adjusting for age, sex, smoking, country, and exposure to other plants or livestock, flower growing was a risk factor for asthma (odds ratio [OR] 2.1, 95% confidence interval [CI] 1.1-3.9) and cultivating oil plants was associated with ODTS (OR 1.5, 95% CI 1.3-1.9), symptoms at work (OR 1.4, 95% CI 1.2- 1.7), and chronic phlegm (OR 1.3, 95% CI 1.1-1.6). Working inside greenhouses was a marginal risk factor for asthma (OR 2.1, 95% CI 0.9-4.5). We conclude that flower and oil plant production is associated with increased risk of respiratory symptoms in European crop farmers.