A stratified random sample among South African Indians living in Durban revealed the occurrence of betel-nut chewing and the resultant submucous fibrosis (SF) to be relatively high. Women chewers predominated in a ratio of 13:1. The habit increased with age and 30.6% of women over 65 years practised the custom. Thirty-eight per cent of chewers revealed signs of impending and established SF; women predominated 70:1, and the majority of sufferers in this instance belonged to the age group 45-54 years (12.9%). Forty-six per cent of those with signs associated with SF had fibrous bands in the mouth and were regarded as having established SF. It was calculated that 5% of the total Indian population in South Africa could be chewers and that 2.3% may develop SF.