Background: Hazelnut has been reported to be one of the most important food allergens. We set out to study whether exposure to hazelnut allergen by occupational contact increases hazel pollen and hazelnut sensitivity and causes workplace-related allergic symptoms in hazelnut processing factory workers. Methods: The study group consisted of 308 employees working in a hazelnut processing factory and 138 subjects with similar age ranges formed the control group. All subjects were asked to fill in a questionnaire about allergic symptoms and then underwent skin prick tests with 9 allergens (Betula verrucosa, Corylus avellana, Quercus robur, D. farinae, D. pteronyssinus, Mould mix, hazelnut, peanut and walnut). Results: There were no workplace-related symptoms in the study group. No significant difference was found in the rate of allergic and respiratory symptoms between the study and control groups. The skin prick tests showed that birch (Betula verrucosa) and hazel (Corylus avellana) pollen sensitivities were higher in the study group than in the control group (p < 0.01 and p = 0.021, respectively). All the other skin prick test results were similar among the two groups. Conclusions: This study showed that occupational exposure to hazelnut caused skin sensitivity to hazel and birch pollen, but this was not associated with an enhanced risk for allergic diseases.