Background: To evaluate prognosis of grade 2-3 endo- periodontal lesions treated nonsurgically in periodontitis subjects. Materials & methods: A total of 100 teeth diagnosed with grade 2-3 endo-periodontal lesions in patients with periodontitis were enrolled. The data was collected and results were analysed using SPSS software. The p-value less than 0.05 was considered significant. Results: No significant differences were found in age or gender between the high and low responder groups (P < 0.05). The significant differences in PD (P =0.001), CAL (P =0.001), full-mouth periodontitis severity (P = 0.002), between the high and low responder groups. Conclusion: High PD and CAL, and serious full-mouth periodontitis indicated a poor prognosis for teeth with grade 2-3 endo-periodontal lesions.