The "conservative" microsurgical lumbar discectomy described by Williams for the treatment of herniated lumbar disc is compared in a retrospective study with the standard microsurgical technique of Caspar and Loew. In order to enable such a retrospective comparison, a special randomization had to be chosen. The data concerning outcome are based on a questionnaire, in which the patient can describe his actual health situation. The result in the group of 56 patients operated on by the Williams technique with a mean follow-up of 27 months is excellent or good in 89% vs. 74% in the standard technique group. Reoperations due to a recurrence were identical in both groups (3.6% and 3.9%).