Abstract A 6-year-old African American boy presented with a 6-month history of nausea, abdominal discomfort, and diarrhea with three to four watery stools a day associated with passage of much gas. These complaints began soon after he started first grade when he was required to drink 2 cups of milk with his school lunch.The symptoms occurred after lunch, and he felt much better after having a bowel movement.No blood was noted in the stool. He was mostly symptom free on weekends, when he rarely drinks milk. There has been no fever or no weight loss, and his appetite has remained good