Leg pain in children, described as“growing pains”, is a frequent clinical presentation. Growing pains include pain late in the day, pain not specifically related to joints, and intermittent manifestation with symptom-free intervals. Physical examination, laboratory tests, and roentgenography show no abnormality. There is no single diagnostic test or criteria for growing pains. Therefore I have proposed new diagnostic criteria which incorporate four conditions as follows : leg-pain less than eight hours in duration, no complaints at visiting hospital, no abnormal findings of physical examination, and normal roentgenograms. If these four conditions can be satisfied, then a clinical diagnosis of growing pains can be made. A retrospective study based on these criteria covering a period of one year demonstrated that the sensitivity of the criteria was 93% and the specificity was 94%. A prospective study covering another year demonstrated the sensitivity of 92% and the specificity of 83%. These new criteria are useful for diagnosis of growing pains.