Purpose: This is randomized, double blind, split mouth clinical study to evaluate the effectiveness of 6% ferric oxalate solution to prevent Root Sensitivity (RS) after periodontal flap surgery. Methods: 25 subjects requiring periodontal surgery in similar bilateral posteriors quadrants were evaluated for RS with tactile, hot and cold test using Visual Analogue Scale (VAS) at baseline and 1, 2, 4, 6 weeks after surgery. Randomization was done with coin flip method for test (6% ferric oxalate in 0.9% saline) or control (0.9% saline) solution for each patient. Solutions were applied to the exposed root surfaces for 1 minute during surgery. Data were analyzed by repeated measures analysis of variance (ANOVA) for inter-group and paired t-test for intra-group comparisons. Results: The test solution significantly reduced RS to tactile, hot and cold stimuliand for more time period than control solution.Sensitivity reduced to 85%, 66% and 53% for tactile, cold and hot stimuli respectively with test solution.Subjects got maximum discomfort on control sites from cold stimulus followed by tactile and least to hot stimulus during 1 and 2 week following surgery. Both the sides showed a gradual reduction in mean VAS, reaching to baseline values at 6 weeks. Conclusion: The application of 6% ferric oxalate during periodontal flap surgery is a rapid and effective means of reducing RS after surgery. It can provide immediate relief to patient in a period when other agents will take longer time to act, thereby preventing discomfort from post-surgical RS.