Abstract Background: About Thirty-five percent of women have severe low back pain after delivery. Phonophoresis is effective in treating acute and chronic back pain. Aim of Study: This study was conducted to compare between the efficacy of Phonophoresis and Transcutaneous electrical nerve stimulation (TENS) on low back pain after delivery. Patients and Methods: This study was carried out on Forty multiparous women suffering from severe Low back Pain For at Least 3 months after delivery. They were selected randomly from the outpatient clinic of orthopedic of Zagazig University Hospitals. Their ages were ranged from 25-35 years old; their body mass index (BMI) didn't exceed 30 kg/m2 and their parity was ranged from (2-4) children. All participants were experienced normal delivery or cesarean section. All patients were divided randomly into 2 groups equal in number, group (A) & group (B). Group (A) received Ketoprofen phonophoresis on her lower back for 10 minutes, 3 times/week for 8 weeks, while group (B) received transcu-taneous electrical nerve stimulation on her lower back (With frequency 80-120 HZ, pulse width 200 us with low intensity) for 30 minutes, 3 times/week for 8 weeks. Low back pain was evaluated by visual analogue scale (VAS) and serotonin level in blood plasma before and after treatment. Results: The results of this study revealed that, both groups (A&B) showed statistically (p-value <0.001) significant decrease in VAS scores and increase in serotonin level in blood plasma after treatment, but the percent of decrease in pain sensation and percentage of increase in serotonin level were more pronounced and more noticeable in (group A) when compared to group (B). This means that, phonophoresis was more effective than TENS in relieving low back pain after delivery. Conclusion: Phonophoresis is more effective than TENS treating low back pain after delivery.