Siddha and Ayurveda are the two major Traditional Indian systems of Medicine. Siddha is widely practiced in the Tamil speaking areas of South India. The frequently prescribed Siddha medicine (Arthoguard) of herbal origin that developed against arthritis was selected and subjected to preliminary phytochemical screening. The extract of the drug was obtained by using ethanol in a maximum yield of phenol. Spectrophotometric analysis indicated that phenols (2.033±0.05 mg mL-1) are the prevalent compounds present in this herbal drug formulation. This result was confirmed with thin layer chromatography. To identify the exact type of phenolic constituents, mass spectrometry was carried out and the compounds were identified as dodecenylacetate, hexadecanoic acid, farnesol and geranylacetate, of which geranylacetate was the principal constituent. This is the first such attempt to provide scientific documentation of this herbal drug. Further studies on the mode of action of these drugs, their immunomodulatory effect, studies related to the understanding the molecular basis of these mechanisms will lead us a long way to position herbal drugs in global market.