The outcomes of mini open discectomy in lumbar disc herniation are usually satisfying. Our study aims at finding if its results are still good at long-term follow-up. We reviewed 552 patients operated between 1993 and 2013 by mini open discectomy procedure. Our main evaluation criterion is a modified Stauffer and Coventry classification applied during follow-up visits at three months, one year, five years, and every five years. The secondary criterion was the Oswestry Disability Index. The outcomes are considered good to very good in 87.3% of the cases at one year follow-up. These results deteriorate after an average follow-up of 14.7 years but remain satisfactory with 63.7%. The global decrease is 23.6%. The Oswestry Score decreases by 35 points at the same follow-up. In addition, 6.52% of patients required fusion at first revision and 1.08% at second revision. We also noticed 51 (9.2%) post-operative recurrences at the same level. In 23 (4.16%) of them, we proceeded to a new discectomy in an average interval of 41.4 months. At an adjacent level, 29 patients (5.2%) presented a new symptomatic disc herniation; among them, eight cases (1.44%) needed discectomy. The re-operative rate (including recurrent disc herniation and fusion for degenerative indications) is 10.68% at the last follow-up. Nearly 2/3 of our patient series keep satisfactory outcomes after about 15-year follow-up. The mini open discectomy remains a reliable surgical technique provided we respect the indications and surgical requirements. This procedure also avoids excessive instrumentation and its possible iatrogenic complications. Powerful randomized and controlled trials are needed to strengthen these deductions.