Aim: this study was to evaluate the response of immature permanent teeth with necrotic pulp and apical periodontitis to two revascularization protocols (Clinical study). Materials and Methods: Twenty upper central incisors with incompletely formed roots from young patients (7 to 18 years old) were selected according to the inclusion criteria. Patients were divided into two groups (10 roots each). Group I; irrigated with 1.5% NaOCl, disinfected using triple antibiotic paste mixed with propylene glycol as a vehicle and revascularization using blood clot. Group II; irrigated with 2% Chitosan, disinfected using triple antibiotic paste mixed with 2% Chitosan as a vehicle and revascularization using blood clot. Each experimental group were subdivided into 3 subgroups (A, B and C) according to the post treatment evaluation period 3, 6 and 12 months respectively. Clinical and radiographic evaluation was performed in 3 follow up periods. Results: Clinical results revealed asymptomatic patient with presence of pulp response to hot sensitivity test in all patients of both groups (I, II) at 12 months follow up evaluation period. Radiographic results regarding increase in root length and resolution of apical radiolucency showed insignificant differences (P >0.05) between the two experimental groups over the three follow-up evaluation periods (3, 6 and12 months). Regarding increase in root thickness, in subgroups A, statistical analysis showed significant difference (P < 0.05) between the experimental groups, on the other hand, the results were statistically insignificant (P >0.05) in subgroups B and C (6 and 12 months) follow-up evaluation periods. Regarding decrease in apical diameter the results were statistically significant (P < 0.05) over the three follow-up evaluation periods (3, 6, 12 months).