The success and failure after treatment of necrotic primary molars causes a hassle to clinicians. This study aims to study the difference between clinical success and radiographic success after treatment using Lesion Sterilization and Tissue Repair technique. The study was conducted on 41 subjects in each group, all subjects were treated by LSTR technique. At the end of the study despite of radiographic failure in 21%from group A & 4% from group B. Molars were clinically successful with absence of pain, swelling, mobility, fistula formation, and were maintained functioning till the end of the study.