The aim of this study was to define the bowel movements of healthy Thai infants up to 12 months of age. Fifty infants were evaluated at 1, 2, 4, 6, 9 and 12 months of age. Data regarding bowel habits was recorded by parents daily for 2 days before coming to the hospital at each visit. The mean frequency of bowel movements per day was maximal (3.16 stools) during the newborn period and declined (1.59 stools) by the age of 12 months. At birth stool consistency was mostly runny, and became consistently more solid by 4 months of age. With increasing age, infants produced larger stools: mean volume of stool was 32.7 ml at 1 month of age and increased to 45.34 ml at 12 months. Infants started to have regular bowel movements at 4 months of age, most of them stopped having bowel movements at night by 3 months.