Introduction. Apexogenesis is the process of shaping the root for 3 years after the appearance of the crown in the oral cavity. The condition for continuing this process is to preserve the vitality of the tooth. Injury, caries or disorders of the anatomical structure may cause necrosis or irreversible pulpitis. The assumption of endodontic treatment of immature permanent teeth is to create a mineralized barrier closing the lumen of the canal (apexification) or continuing the development of the root (revascularization). Regeneration of the pulpo-dentinal complex allows for the increase of root length, thickening of its walls and narrowing of the apical hole. This can be achieved by a new treatment method – revascularization. The advantage of this therapeutic method is to avoid all the defects arising after endodontic treatment with the use of apexification, i.e. tooth brittleness, susceptibility to root fracture, discoloration of the tooth tissue. Aim. The aim of the study was to evaluate the modern method of treatment of necrosis or irreversible pulpitis in immature permanent teeth by revascularization in the aspect of tissue healing, regeneration of the pulp-dentinal complex, thickness growth and the length of the root walls. Material and methods. The study was conducted among 7 children aged 7-12, including 3 girls and 2 boys. Revascularization was performed in 7 teeth. The study involved 6 central incisors and 1 premolars. During the treatment, polyurethane paste and MTA were used. The control group consisted of patients who were tested using MTA due to the inability to perform revascularization. 23 patients aged 7-13 were qualified to the control group. Control tests were carried out after 3, 6, 12 months after treatment. The clinical condition of the tooth and the radiological image were evaluated. Results. Radiological examination was crucial in assessing the effectiveness of the revascularization procedure. It confirmed the decrease of periapical lesions, increase in root length, root wall thickness and closing of the apical hole. During the clinical examination, the subjective feelings of the patient, discoloration of the tooth's tissues, reaction to tapping, tooth mobility, depth of the gingival pocket, tenderness of the appendage and tightness of the final filling were controlled. The obtained results were compared with the control group. Conclusions. Revascularization is a promising treatment for immature permanent teeth due to the increase in the length of the root and the thickness of its walls. As a result, the teeth after treatment are more durable and are better for long-term maintenance in the mouth. The procedure of revascularization has some limitations at the stage of patient’s qualification for the procedure. If it is not possible to perform this procedure, the alternative is to apexify using MTA.