The study’s main objective is to evaluate the inhibitor effect of Bryophyllum pinnatum leaves extracts/fractions on the crystallization of calcium oxalate in synthetic urine. The study of calcium oxalate crystallization is based on changes in turbidity. The effect of Bryophyllum pinnatum leaves extracts/fractions on the crystallization of calcium oxalate was evaluated. Calcium oxalate crystals formation is caused by adding 10 to 50 mM sodium oxalate solution to synthetic urine. Adding extracts/fractions of B. pinnatum leaves (i.e., petroleum ether/chloroform/ethyl acetate/methanol/aqueous extract and ethyl acetate/ methanol fractions) allowed us to provide information on the inhibition percentage. The ethyl acetate and methanol extract/ ethyl acetate fractions-9,10 / methanol fractions-3,4 of B. pinnatum leaves displayed a maximum nucleation inhibition of 85.50, 91.03/73.62, 73.79/75.34, 77.24 percent observed at 10mg/ml and 5 mg/ml concentrations. The nucleation inhibition percentage of cystone is 57.24 at 10mg/ml. A potent dosedependent aggregation inhibition was shown in the aggregation assay of ethyl acetate and methanol extract of B. pinnatum leaves, with a percentage inhibition of 74.62 and 84.7 percent. The ethyl acetate fractions9, 10 with a percentage inhibition of 70.14 and 77.12 percent, and the methanol fractions-3, 4 with a percentage inhibition of 69.37 and 74.62 percent. In calcium oxalate nephrolithiasis, the ethyl acetate, methanol fractions, and ethyl acetate fractions-9, 10, methanol fractions-3, 4 of B. pinnatum leaves strongly inhibit crystal formation. The aggregation inhibition of cystone is 70.84.