Three cases of Crohn's disease (CD) which showed an elevation of creatine phosphokinase (CPK) during the course were reported. In two cases, elevations of serum myoglobin and aldolase were also observed which indicated rhabdomyolysis. Rhabdomyolysis occurred unrelated to the activity of CD and it was asymptomatic. It was unable to identify an apparent known cause for rhabdomyolysis. All three cases were under elemental diet (ED) but the causality of ED for rhabdomyolysis was uncertain. So far as we know, there is no report on rhabdomyolysis during ED treatment and there are only two reports in which rhabdomyolysis was documented in CD. The latter was rhabdomyolysis due to electrolyte depletion secondary to malabsorption in CD which was not encountered in our cases. Our department dealt only three cases of CD and all of them had an elevation of CPK which had been measured as one of routine blood chemistry in our hospital. These observations led to a following conclusion that subclinical rhabdomyolysis may be one of extra-intestinal complications of CD.