Children suffering from Gaucher's disease were examined by magnetic resonance imaging (MRI) during a characteristic episode of "bone crisis". An unexpectedly high intramedullary as well as subperiosteal signal was observed on both the T1- and T2-weighted sequences in 5 patients, suggesting a subacute hemorrhage or hematoma. It is conceivable that such a painful hemorrhage is an important component of the "bone crisis" phenomenon. Furthermore, in these cases this is a specific sign which may enable differentiation of bone crises from other types of bone pain associated with Gaucher's disease.