As reoperations on patients with lumbar disc herniation are usually successful, a careful study of the cases considered as surgical failures or relapses was made. Among 360 laminectomies and hemilaminectomies for herniated lumbar disc 22 cases needed to be reoperated on. The cases were classified in two groups: 1 - failure caused by technical problems at the first operation, 8 cases (in two of them a wrong disc was explored, in 5 the disc was not removed or was only partially curetted, in one a cotton pad was left); 2 - relapses, 14 cases (4 were caused by fibrosis, 9 by a new prolapse in another disc and one by herniation in the same disc, at the other side). This study allowed the following conclusions: decompressive operations are not justified; the herniated disc must be completely curetted; after operation the patient must have physiotherapie care and avoid physical strain; myelography is the best test to be done when reoperation is considered.