In order to survey the adulteration of synthetic chemical drugs in antirheumatic and analgesic Chinese medicine, we collected 155 samples randomly in Taiwan area from Sep. 1985 to May 1986. The results of thin-layer chromatographic and UV spectrophotometric analysis indicated that 12 samples (7.74%) were adulterated with synthetic drugs, including Ethoxybenzamide, Caffeine, Ibuprofen, Indomethacin, Acetaminophen, Diclophenac Sodium, Chlorzoxazone, Hydrochlorothiazide, phenacetin and Mefenamic acid etc.