Nickel workers and wood workers have an increased incidence of carcinoma and of lesions of the nasal mucosa regarded as precancerous, i.e. dysplasia. This preliminary study demonstrates how metaplastic and dysplastic changes of the nasal epithelium may be diagnosed independently from cytological smears and from histological sections of samples from the same middle nasal turbinate. The sampling technique described yielded excellent material for cytological diagnosis and was also suitable for detailed cell surface characterization by scanning electron microscopy (SEM). Exfoliative cytology was found to be a reliable means of detecting preneoplastic changes in the nasal mucosa of individuals in selected risk groups. The sampling procedure causes less discomfort to the subjects and requires fewer resources than biopsy procedures.