In vitro sonography and piezoelectric lithotripsy(EDAP LT.01) of 22 gallstones were done to assess the relationship between the sonographic characteristics of gallstones and fragmenation patterns. The gallstones were classified based on their sonographic characteristics into three types: type 1(surface echo gradually changing to acoustic shadow, n=6), 2(surface echo abruptly changing to acoustic shadow, n=6), and 3(well discerned entire stone echo with indistinct acoustic shadow, n=10). Fragmentation patterns were classified by gross morphology of fragments into three pattern: pattern A(powder-like), B(sands/pebbles-like), and C(fracture rather than pulverization). Patterns A was observed only in gallstones of type 1. Gallstones of type 2 or 3 showed pattern B or C, No significant differences in fragmentation patterns were found between type 2 and type 3. These results suggest that fragmentation pattern of gallstones is possibly affected by their sonographic characteristics. Therefore, these data should be useful in predicting fragmentation patterns and selecting patients eligible for lithotripsy.