Oral submucous fibrosis (OSF) is a pre-cancerous condition caused by the use of areca nut in various forms. There are very few published reports on areca nut use and OSF from Chennai, South India. A hospital-based case-control study on habits and OSF was performed in Chennai over a 3-year period. A total of 185 consecutive patients with OSF were matched with age- and sex-matched controls. History was recorded in a pre-determined format by qualified dental surgeons. The male to female ratio of OSF cases was 9.9 : 1. All areca nut products were associated with OSF, with the risk being greatest for pan masala. The duration of the habit was more significant than the frequency of the chewing habit. The present study confirms the strong association between areca nut use and OSF and the increasing use of pan masala.