This study has been conducted to determine efficacy of the brief intense TENS on pain in patients with post – herpetic neuralgia of sciatic nerve. Forty patients (25 males and 15 females) suffering from post –herpetic neuralgia with no other systemic or metabolic disorders, participated in this study. Their age ranged from 25 to 40 years (X=34.35± 1.11). They were divided randomly into two groups of equal number and consented to receive brief intense TENS (for the first experimental group) and placebo TENS (for second control group), from a dual – channel TENS unit along the sciatic nerve course. Assessment of pain was carried out before and after treatment which include a session for 10 minutes conducted every twelve hours daily, at the same times on 3 consecutive days. Non significant difference in serum cortisol level was recorded before starting the treatment between the two groups as it was 34.35 and 34.30 for the first and second group respectively. Data collected at the end of the treatment program showed that averages of Serum Cortisol Level (SCL) were 26.59±2.71 µg/dl and 34.28±3.49µg/dl in the first and second groups respectively. Results showed a significant reduction in SCL at the end of the treatment program in the first group only. So the brief intense TENS may be considered as an effective tool in modulating the post –heretic neuralgia of the sciatic nerve.