This review focuses on the major cellular and structural changes in the airways in occupational asthma and underlines mechanisms that contribute to airflow limitation found in asthmatic patients. Asthma is characterized by thickening of the airway wall and developing of the inflammatory process, including infiltration of inflammatory cells, release of a wide spectrum of molecules (fibronectin, growth factors, cytokines and chemokines), deposition of immunoglobulins and collagen, smooth muscle hyperplasia and fibrosis. These cellular and structural changes may contribute to thickening of the reticular basement membrane and the stable increase in airflow limitation. Airway remodeling is of clinical importance in occupational asthma because it is the main reason for persistent, progressive impairment of respiratory function and makes it necessary to re-evaluate the patient's respiratory disability two years after cessation of occupational exposure.