BACKGROUND Till a national campaign against dust-related lung diseases was launched by a voluntary agency in Ahmedabad in 1992, government records for the 150-year-old textile industry showed no cases of byssinosis--the disabling occupational disease caused by cotton dust. The worldwide incidence of byssinosis among workers in the dusty sections of textile mills is nearly 40%. We assessed the prevalence of byssinosis in a Bombay mill so that the Employees State Insurance Scheme would start conducting medical checks in all the 55 textile mills in Bombay and officially recognize the disease. METHODS The study was conducted under the auspices of the Occupational Health and Safety Centre, a voluntary organization. Textile workers were called to a camp conducted over 3 nights and 3 days. We asked them to answer a questionnaire and tested their lung function using a Wright's ventilometer. The diagnosis of byssinosis was made if there was a feeling of chest tightness on exposure to cotton dust, and if the FEV1 was less than 60% of the expected result or the FEV1/FVC was less than 75%. RESULTS Of the total 1075 workers in the mill only 273 came to the camp; 54 (30%) of the 179 individuals working in the dusty sections of the mill had byssinosis. In the non-dusty departments, 16 (17%) out of the 94 workers were affected. Among those working for less than 10 years in textile mills, 24% had byssinosis and among those working for more than 30 years, 45% had the disease. CONCLUSIONS We found a prevalence of byssinosis among textile workers which is similar to that reported worldwide. The disease affected those who worked in both the dusty and non-dusty sections of the mill. There are an estimated 40,000 affected workers in Bombay and we suggest that the disease be recognized by the Employees State Insurance Scheme, and that the textile mill workers be compensated if they are affected by byssinosis.