Objectives. To describe the patterns of and factors affecting breastfeeding and to find out any significant relationship between breastfeeding and health of the child. Design. Cohort study. Setting. Postnatal ward of the Prince of Wales Hospital. Participants. A total of 243 infants born in 1998 to 2001 at the hospital. Each infant was followed up for 3 years. Home visits were carried out at 3, 15, 24, and 36 months of age by medical students from the Chinese University of Hong Kong. A questionnaire was completed at each visit. Independent sample t-tests and Pearson Chi squared tests were used. Results. Of the 243 subjects, 213 provided data on the method of infant feeding. There were 66.7% of mothers initiating breastfeeding, with a median duration of 1 month. Only 13.4% met the World Health Organization's recommendations on breastfeeding. Breastfeeding was found to have a statistically significant relationship with (i) the infant's birth order and (ii) the mother's and father's education level. During follow-up, 44.6% of the infants were hospitalised but there was no significant relationship between breastfeeding and number of hospitalisations. Conclusions. The current breastfeeding rate in Hong Kong falls below expectations when compared with other developed nations. To raise this rate, more support is needed for families with parents having a lower education level or more than two children, as they are the least likely to breastfeed. This might be achieved by encouraging antenatal class attendance, counselling of husbands, and more support for breastfeeding from doctors.link_to_subscribed_fulltex