The Authors present a series of 7 cases of late myelitis consequent on radiotherapy in patients treated for Hodgkin's lymphoma. These 7 cases represent 1.4% of the 500 cases of Hodgkin's lymphoma subjected to radiotherapy at the Istituto Nazionale Tumori of Milan from 1970 to 1980, and all concern the dorsal tract of the spinal cord. They were found at an interval varying from 5 to 13 months after radiotherapy. The 7 cases were treated with equivalent doses varying from 951 to 1077 rets. The possibility is discussed to further reduce the incidence of these lesions from radiotherapy to less than 1%, administering equivalent doses lower than 1015 rets, without increasing the risk of recurrences of the disease.