The purpose of this work was to study the appearance of infantile colic and gas discomfort and to learn whether these problems are associated with factors in the child's social environment, allergic symptoms, or feeding. The study was made retrospectively by means of a questionnaire which was sent to mothers of every tenth child aged 14 to 38 months in Turku, Finland. Forty percent of the children, as many boys as girls, had colic or gas problems in early infancy, so severe in 20% that drug therapy was used. First born children in the family more often had colic and gas problems than did subsequent children. Siblings of colicky children had colic and gas problems more often than did siblings of the children who had no colic or gas problems. Neither family history or symptoms of allergy, duration of breast-feeding, mother's consumption of plain cow's milk during lactation, nor the age of introduction of cow's milk to the child were associated with the occurrence of colic. Children with colic grew as well as children without. However, their night sleep was more often disturbed by awakenings than the night sleep of children without colic or gas problems in early infancy.