A method of evaluation for in vitro inhibitory effect on kidney stone was adjusted and implemented on ethanol residual from herbal extract. The influence of ethanol on calcium oxalate crystallization was investigated, and 20 percent ethanol in water was chosen as solvent. The method was implemented on ethanol extract residual from 7 Ficus L. species (F. racemo5a, F. benga/ensis, F. hispida, F. auriculata, F. pumila, F. rumphii and F. religiosa). It was observed that extract from 2 plants manifested inhibition on calcium oxalate crystallization, i.e. F. rumphii and F. pumila, among which F. pumila shows more convincing results. The rest 5 species did not manifest obvious inhibition on calcium oxalate crystallization, only F. racemosa, F. auriculata, and F. re/igiosa increased the ratio of COD (crystal form of calcium oxalate which can more easily be excreted). For F. pumila, the results in both 620 nm absorption and microscopic image showed the inhibition effect in terms of a decrease in amount of crystals, as well as an increase in COD/COM ratio. The inhibition percentage was 27 percent for the solution of 100 ug/mL, and EC50 and 1C50 was 44.9 percent and 53.8 ug/mL, respectively, for F. pumila. The effect of F. pumila increased over higher concentration of extract, exhibited same tendency with the positive control, sodium citrate, but much lower potency of effect was observed, compared with EC50 of 148.2 percent and 1C50 of 0.72 ug/mL for sodium citrate, determined in the same conditions.