The term "Entrapment" was first used by Russel Brain in 1947 to describe compression of a nerve in a closed compartment created in a fibrous or fibra-osseous tunnel through which the nerve should pass in its normal anatomical course. The nerve roots gain their exit to the exterior through conduits or tunnels and not through simple intervertebral foramina as was previously conceived. The attitude in tackling the lumbo-sciatic problem should be changed according to this concept and we should now manage this problem in terms of decompression of the affected nerve roots rather than in terms of simple disc surgery. This attitude has been made more feasible with the use ot contrast examination of the epidural canal - epidurography - in investigating these cases. The aim of this thesis is to discuss the anatomy, pathogentsis and pathology of lumbar nerve root entrapments and to present and discuss the clinical, epidurographic and operative findings in thirty patients treated at El-Zatoun Orthopaedic Hospital in Cairo for lumbo-sciatic problems.