Two caystalline substances were isolated from the Chinese drug "Chin Pie", which is the bark of Fraxinus rhynchophylla Hance. They have been identified as 6,7-dihydroxy coumarin and 6 (6,7-dihydroxy-coumarin)-β-D-glucoside respectively, Both of them can inhibit the growth of dysentery bacilli of Flexner, Sonner, and Schmitz types in vitro. Preliminary clinical studies on the treatment of dysentery patients showed that esculetin has significant curative effect by oral administrations.