Leprosy is a chronic infectious disease endemic in Iran that mainly involves skin and peripheral nerves. Leprosy has several clinical forms. One of them is “Pure neural leprosy”. The diagnosis of this form is delayed due to lack of clinical signs in other tissues and can lead to permanent deformity. I will discuss my experience for 20 years in the diagnosis and treatment of this form of leprosy and will report a case. Definite diagnosis is usually possible by biopsy of an involved peripheral nerve. Biopsy from uninvolved nerve might give inconclusive results (Sometimes biopsy is taken only from sural nerve) but typical changes of neural leprosy can be found in involved nerves in the same patient. Nerve biopsy can also help in the classification of leprosy and differentiation of leprotic neuritis from neuritis in leprosy reactions. The main complication of nerve biopsy is a local anesthesia of the skin, which usually improves spontaneously. Considering the absence of neurosurgeons in most endemic areas of leprosy, it is recommended to train physicians involved in leprosy treatment to do nerve biopsy.