Background: Hence; the present study was conducted for comparing the outcome of single sitting root canal treatment done with reciprocating and rotary files. Materials & methods: 100 patients with acute pulpitis requiring root canal therapy on mature permanent mandibular molars were selected for the study. A total of 100 teeth which required endodontic treatment were randomly divided into two groups: -1 . Group I consisted of eighty (50) mandibular molar teeth treated in single visit with single file rotary endodontics (Fig 1-Wave one). 2. Group II consisted of eighty (50) mandibular molar teeth treated in single visit with multi file rotary endodontics. The patient carried the VNRS scale form along with them. Pain was recorded preoperatively in front of operator. After this pain was recorded by patient on the scale postoperatively at 12hrs, 24hrs, 48hrs, 72hrs, 1 week. VNRS scales and record of medications taken were collected from the patients. The data was compiled and statistically analyzed. Results: The mean pain score in mandibular molars treated in Group I preoperatively, at 12 hrs, at 24 hrs, at 48 hrs, 72 hrs and 1 week was 5.16, 0.66, 0.20, 0.0, 0.0 and 0.0 respectively. In Group II preoperatively, at 12 hrs, at 24 hrs, at 48 hrs, 72 hrs and 1 week mean pain score was 4.51, 0.64, 0.43, 0.03, 0.0 and 0.0 respectively (Table 3). Results showed that there was no statistical difference of pain in between both groups at different time intervals and was significant only preoperatively (Table 4). The mean number of analgesic tablets taken in Group I was 0.33 and in Group II was 0.35. Results showed there was no significant difference in analgesic tablets taken between two groups (Table 5). Conclusion: From this it can be considered that if all the protocols of endodontic treatment are followed judiciously than single visit endodontic treatment can be done effectively using either single file endodontic system or multi file endodontic systems as outcomes are almost similar. Key words: Root canal, Rotary