We have compared the histological aspects of nasal mucosa biopsies (n = 130) obtained during bilateral polypectomy and ethmoidectomy performed in black African (n = 50), Chinese (n = 30) and Caucasian patients (n = 50) suffering from bilateral nasal polyposis (NP). The three groups of patients were matched for age and sex. The African and Chinese patients did not receive any medical treatment before endoscopic nasal surgery (ENS). All Caucasian patients were treated with corticosteroid nasal spray (400 mg/day) for 6 months. In the absence of subjective and objective clinical improvement, ENS was performed after antibiotic treatment for 10 days and prednisolone 1 mg/kg/day for 5 days. Clinical staging of the NP was graded from I to III (I = polyps limited to the middle meatus, II = polyps extending beyond the middle meatus, and III = polyps occupying the entire nasal cavity). Stage I NP was present in 22% of the Caucasians and 30% of the Chinese. Stage II was found in 58% of the Caucasians, 56% of the Chinese and 8% of the Africans. Stage III was found in 92% of the Africans, while only 20% of the Caucasians and 14% of the Chinese patients had stage III. The extent of submucosal oedema and number of mast cells were similar for the three groups of patients. A significantly greater number of eosinophils were observed in African polyps. Lymphocytes as well as plasmocytes were rare in African but abundant in polyps from both Chinese and Caucasian. Ulceration of the overlying epithelium of the polyps was observed in 20% of the African and 10% of both Chinese and Caucasians patients. We did not find any significant thickening of the basal membrane. We cannot exclude the possibility that the histological difference observed between African and Chinese polyps is related to the very common use among the Chinese population of topical intranasal treatment according to their traditional medicine practices. Since no major histological difference was found in the nasal mucosa and polyps obtained from the three groups of patients, NP in African, Chinese and Caucasian patients is very probably a similar inflammatory disease in all three ethnic groups.