This study was conducted to examine the development of a new anti-inflammatory substance with potent anti-inflammatory activities that was derived from the Platycodi Radix butanol fraction. To accomplish this, the chemical structures and anti-inflammatory activities of the components were elucidated. Upon column chromatography of the tertiary subfraction, fractions 8-4-1 and 8-4-2 were identified as platycodin D and D3, respectively, following recrystallization, based on melting point (MP), infrared (IR), and positive fast atom bombardment (FAB)-mass and nuclear magnetic resonance (NMR) spectral data. Platycodin D and D3 exhibited strong anti-inflammatory activities in rats when administerd at oral doses of 12 mg/kg and 36 mg/kg, p.o., respectively. Platycodin D and D3 induced inhibitory effects on capillary vascular permeability in rats at oral doses of 16 mg/kg and 24 mg/kg, p.o., respectively, and potent inhibition of leukocyte emigration in a carboxymethyl cellulose (CMC)-pouch when administered at doses of 3 mg/rat and 7 mg/rat, s.c., respectively. These results verified the high antiinflammatory potency of the platycodin D and D3 components in Platycodi Radix.