Background: “Jamu Pegal Linu” (traditional Indonesian herb for rheumatoid and gouty arthritis) is one of the mostpopular jamu products manufactured and widely consumed in the community. Despite the claims that they are made ofnatural herbs, these kinds of jamu are susceptible for being counterfeited and adulterated with drugs that is potentiallyharmful for health. The aim of this study was to identify medicinal adulteration in jamu pegal linu products obtained from the market in Jakarta and surroundings. Method: This study was an experimental laboratory in a cross-sectional design. About 450 samples of jamu pegal linu products were randomly chosen, and the products with different brands wereanalyzed for medicinal adulteration using a thin layer chromatography (TLC) method. Product labels of the adulterated jamu were also analyzed for the appropriateness of the product information. Results: Out of the 114 brands of jamu pegal linu analyzed, 52 samples (45.6%) were positive for medicinal. The medicinal types detected were paracetamol (30.7%), phenylbutazone (20.4%), piroxicam (7.1%) and mefenamic acid (3.5%). Two samples of jamu has been contaminated with molds and found damp. Of the 52 samples positive medicinal, 92.3% include the registration number and only 30.8% include the expiration date in the product labels. About 44.2% include the name of ingredients compositions written incorrectly in the labels. Conclusion: A. limited numbers of Jamu pegal linu products adulterated with medicinal still existed in the market.