Anomalies of lumbosacral nerve roots, even though are rare, have been well documented so far in the medical literature. The early diagnosis of these anomalies may be difficult and it is crucial to develop specific methods for depicting them. Preoperative diagnosis of anomalous lumbosacral spinal nerve roots using the magnetic resonance imaging is essential to facilitate thorough surgical planning in order to avoid unnecessary complications for the patient during surgery. The operative management of these anomalies depends on the patient's neurological problems and while asymptomatic and accidentally diagnosed cases do not require treatment, patients who suffer low back or sciatic pain need surgical intervention in order to decompress nerve roots. We report a 45-years old woman presented with severe low back pain associated with left lumboischialgia. Intraoperative finding of an aberrant L5/S1 nerve root, optimal surgical therapy and different classifications are discussed together with a review of literature.