The histological study of the non-tumours nasal mucosa in 22 wood-workers with ethmoidal adenocarcinoma was carried out and special attention was paid to the presence of cuboidal metaplasia with or without dysplasia. The workers had been exposed to wood dust for an average of 38 years (range 18 to 55 years). In 19 cases cuboidal metaplasia was found and 16 of these also had dysplasia. In 10 cases there was a transitional zone with dysplastic cuboidal epithelium in continuity with the tumour. In 5 cases there was squamous metaplasia. The results indicate cuboidal metaplasia with dysplasia being a possible precursor to nasal adenocarcinoma in workers exposed to wood dust, similar to the findings of squamous metaplasia and squamous cell carcinoma in nickel workers.