Purpose. To determine the effect of interferential current augmented by strengthening exercises for core muscles on low back pain after delivery. Design. single blind randomized controlled trial. Methods. Thirty multiparous women suffering from postpartum low back pain (for at least 3 months after delivery) participated in the study, they were selected randomly from the outpatient clinic of obstetrics and gynecology in Police Authority Hospital at Naser City, Cairo, Egypt; their ages ranged from 25-40 years old, through a period of 33 months (from May 2017 to February 2020). Confidentiality was assured. They were assigned randomly into two groups equally in number; 15 patients each: Group (A) patients received interferential current on the lower back for 20 minutes, 3 times /week for 4 weeks, additionally to this, they were asked to perform strengthening exercises for back & abdominal muscles, posterior pelvic tilting and postural correction exercises for 60 minutes, 3 times / week for 4 weeks. Group (B) patients were asked to perform strengthening exercises for back& abdominal muscles, posterior pelvic tilting and postural correction exercises for 60 minutes, 3 times / week for 4 weeks. Results. Comparing both groups post-program revealed that there was a highly statistically significant reduction in present pain intensity scale and serum cortisol level (p < 0.05) in favor of the group (A). Conclusion. interferential current augmented by strengthening exercises for core muscles had a significant effect on low back pain after delivery, so this study supports the value of interferential current on low back pain after delivery patients.