Occupational rhinitis (OR), a very frequent disease caused by several occupations, tends to share etiological agents and to be three times more prevalent than occupational asthma (OA). Exposure, which can be reliably estimated by means of job description or mean week exposure, may be the single most important determinant of occupational sensitization and OR. Atopy is a controversial risk factor for OR and a major risk factor for occupational sensitization when high molecular weight agents are involved. The role of smoking in OR and occupational sensitization is not clear and has yet to be explained in full.