This review is intended to critically examine the notion that physical training, in addition to its nonspecific effects on fitness, can induce disease-specific benefits in the child with a chronic disease. Conditions included in this analysis are asthma, cerebral palsy, coronary risk, cystic fibrosis, diabetes mellitus, hypertension, myopathies, and obesity. Most of the published intervention studies are deficient in design by not including randomly assigned (or matched) controls. Other constraints stem from the need to simultaneously maintain other therapeutic modalities, the progressive nature of some of the diseases, and the small pool of suitable subjects.