Dog rose fruits and hibiscus petals were extd. with CH2CH2 at 60 degrees C for 8 h to remove essential oils and then with MeOH at 50 degrees C or with 0.1 M NaOH at room temp. for 48 h. The exts. were used in aq. solns. for dissolving model (Ca oxalate) or post-operative kidney stones at 20 degrees C for 120 h. The leachates were analyzed for Ca and the solid phase for morphol. The hibiscus exts. showed high ability for dis-solving the stones.