A survey of the oral mucosa in 661 of the people living in various geographical locations of the Gizan region has been carried out. Mucosal lesions compatible with 'oral leukoplakia' have been found to affect approximately 68% of the users of the native snuff known as 'Shammah'. The lesions were almost always at the site where 'Shammah' was habitually held. Histological examination of biopsy specimens obtained from 29 different individuals revealed squamous cell carcinoma in 7 cases and carcinoma in situ in 2 cases, whereas the remaining specimens showed ortho- and para-hyperkeratosis, some of which also had premalignant changes. The results of this study point to a possible causal relationship between the use of 'Shammah' and the development of oral premalignant and malignant lesions among snuff-dippers in the Gizan region.