101 patients with lumbar disc herniation were treated by transforaminal endoscopic microdiscectomy between 5/94 and 6/97. Caused by technical problems the procedure could not be successfully completed in 3 patients. They must be excluded from the presented study as 9 others, who were lost for follow up. So 89 patients were followed with a median follow-up time of 28 months (15-56 months). 69 patients (78 %) were satisfied. 16 patients needed a second operation. In 11 of these 16 patients it was done by an open procedure, in 5 by transforaminal endoscopic microdiscectomy again. 4 of these 5 patients showed a good or satisfying result. As in open procedures the most important prognostic factor is a promptly disappearing radicular leg pain. Only 6 of 61 patients with a radicular leg pain disappearing within one week were reoperated, but 10 of 28, who showed a leg pain persisting longer than one week postoperatively.