Aim and objective: This case study's objective is to illustrate how regenerative endodontic procedure (REP) can be used to treat an immature necrotic tooth with symptomatic apical periodontitis. Background: Endodontics is transitioning into a new era of tissue engineering and regeneration. We may need to adopt a more biological strategy to encourage the body’s innate wound healing process to revitalize the pulp tissue within the canal space rather than routine root canal treatment for immature necrotic teeth. Compared to apexification procedure, outcome studies using REP on immature permanent teeth showed larger improvements in both root width and root length. Case description: In this case report, a 14-year-old female patient came in with a chief complaint of pain in her lower right premolar tooth. On clinical examination deep dentinal caries was revealed, radiographically; periapical radiolucency was seen with an immature root and wide open apex. A finding of immature permanent tooth with symptomatic apical periodontitis was confirmed. Regenerative endodontic procedure (REP) was chosen as the course of treatment. Local anesthesia was administered, access opening of the tooth#45 was carried out, radiographic measurement of the working length was done and the tooth was biomechanically preparated upto 30k file. Calcium hydroxide dressing was given for 1 week. Following week TAP ( triple antibiotic paste) was placed for about 2 weeks. After complete disinfection of the canal , in the 3 rd week blood clot was induced within the canal using a sterile 15k file 2mm beyond the apex. PRF fragment membrane using an endodontic plugger was placed into the pulp chamber. Biodentine was placed over the PRF membrane and the tooth was restored with GIC. The patient underwent evaluations after 3, 6, 9 and 12 months