Aim: to evaluate effect of Biodentine and MTA on the root length, root dentin thickness and apical diameter after revascularization in necrotic immature permanent teeth. Subjects and methods: 20 upper anterior teeth showed immature roots with an open apex, ranging in age from 9 to 12 years. Revascularization treatment was done, which was started with disinfection of the canals (sodium hypochlorite irrigation, followed by triple antibiotic paste for 2- 3 weeks). Next, the triple antibiotic paste was removed by irrigation with saline, The teeth were divided into two groups 10 each Group A: revitalization using blood clot scaffold only, and Group B: revitalization using blood clot and platelet rich fibrin (PRF). Each group was subdivided into two subgroups according to the material placed over the root canal orifice and a coronal seal of glass ionomer. Follow-up was done for 6 months. Standardized radiographs were analyzed for the peri-radicular healing and apical closure.. Results: There was significant decrease in the mean apical diameter along the follow up periods. No significant differences were shown between all groups. Conclusion: Clinical and radiographic evidence showed, revascularization procedure could be an alternative treatment in immature nonvital teeth. In addition, placing Biodentine and MTA cement provided a good seal and favorable outcomes