Introduction: Rheumatoid arthritis (RA) is one of the most challenging diseases due to its chronicity, incurability, complications and morbidity. It is an auto-immune inflammatory disease. From Ayurveda point of view, this disease can be correlated with Amavata in its clinical presentation. In spite of potent anti-inflammatory and powerful immunosuppressive agents; itsprognosis is bad and these drugs are associated with certain side effects too. Ayurveda holds various formulations for this condition and Amavatari Rasa, a mercurial formulation is one among them. Aim of the current study is to evaluate impact of Mercury on the efficacy of Amavatari Rasa in Rheumatoid Arthritis through double blind trial. Methods: Total 86 patients were registered and randomly divided into two groups and were treated with Amavatari Rasa prepared in absence of mercury (ARM) and Amavatari Rasa with mercury (ARC) at dose of 250 mg thrice a day, 30 minutes before meal with luke warm water for 8 weeks. Assessment was done on the basis of clinical recovery, symptomatic relief and pathological investigations. Results: At the end of the trial; the nature of the trial drugs was unveiled.Both the formulations showed highly significant results (p<0.001) in all the signs and symptoms except trishna (thirst). Majority of the signs and symptoms were better relieved with ARM group, whereas biological markers corrected with ARC group. Though, there is no significant difference in between the results of both the groups, ARC appears to be influencing the cellular level of pathology, while ARM is helpful in providing symptomatic relief. Conclusion: Thus, it can be inferred that, presence of mercury is essential that helps in taking the drug to the cellular levels and breaking the pathology successfully. No untoward effects were noticed in any patients during the study period.