In an urban slum in eastern Kolkata, India, reported diarrhoea rates, healthcare-use patterns, and factors associated with reported diarrhoea episodes were studied as a part of a diarrhoea-surveillance project. Data were collected through a structured interview during a census and healthcare-use survey of an urban slum population in Kolkata. Several variables were analyzed, including (a) individual demographics, such as age and educational level, (b) household characteristics, such as number of household members, religious affiliation of the household head, building material, expenditure, water supply and sanitation, and (c) behaviour, such as hand-washing after defecation and healthcare use. Of 57,099 study subjects, 428 (0.7%) reported a diarrhoea episode sometime during the four weeks preceding the interview. The strongest independent factors for reporting a history of diarrhoea were having another household member with diarrhoea (adjusted odds ratio [OR]=3.8; 95% confidence interval [CI] 3.3-4.4) and age less than 60 months (adjusted OR=3.7; 95% CI 3.0-4.7). The first choice of treatment by the 428 subjects was as follows: 151 (35%) had self- or parent-treatment, 150 (35%) consulted a private allopathic practitioner, 70 (16%) went directly to a pharmacy, 29 (7%) visited a hospital, 14 (3%) a homoeopathic practitioner, 2 (0.5%) an ayurvedic practitioner, and 12 (3%) other traditional healers. The choices varied significantly with the age of patients and their religion. The findings increase the understanding of the factors and healthcare-use patterns associated with diarrhoea episodes and may assist in developing public-health messages and infrastructure in Kolkata.