The purpose of this study was to elucidate the feasibility of microendoscopic discectomy (MED) for the treatment of lumbar disc herniation with a bony fragment due to apophyseal separation. Eighteen patients with low back pain and unilateral sciatic pain due to lumbar disc herniation with a bony fragment were treated by MED using the unilateral approach (15 males and three females; mean age, of 28.9 years; mean follow-up period, 21.1 months); 18 age-and sex-matched patients with lumbar disc herniation without a bony fragment treated by MED served as the control group. The clinical outcomes were evaluated using the Japanese Orthopedic Association Score for Low Back Pain (JOA scores; maximum score, 29 points). Evaluation of the results revealed that good surgical outcomes equivalent to those in the control group were obtained in the subjects of LDH with a bony fragment (JOA scores; 14.1+/-3.5 in the patient group vs.15.4+/-2.6 in the control group before surgery; 26.3+/-1.8 in the patient group vs. 26.9+/-1.3 at follow-up after the surgery). Although the mean surgical time was significantly longer in the patient group, there were no intra- or postoperative complications in either group. We conclude that MED using the unilateral approach is a feasible minimally invasive surgical option for patients of lumbar disc herniation with an apophyseal bony fragment.