Cholecystectomy causes alterations in bile composition. In particular it rises the proportion of highly detergent bile acids with the possible consequence of the manifestation of dyspepsia in a high percentage of patients: this is the well-known post-cholecystectomy syndrome. In this clinical trial we studied the activity and safety of tauroursodeoxycholic acid--TUDCA--(500 mg/die) in the prevention of dyspepsia in cholecystectomized patients, in comparison with no treated group. We enrolled 203 patients (101 TUDCA--group A--and 102 control-group B). The two groups were comparable for age (47.1 years in group A and 50.7 years in group B), sex (m/f: 28/73 and 37/65 in the two groups) and for other characteristics connected to surgical procedures. After operation all patients suffered from dyspepsia symptoms. In patients treated with TUDCA we registered a prompt regression in severity of symptoms when compared with no treated group: in fact we noted a significant difference only at the first control planned after one month from operation. No difference were registered at the other controls (two and three months after operation). Two patients in A and 3 in group B manifested adverse events. In conclusion, the treatment with TUDCA, a new hydrophilic bile acid, seems to contribute to the improvement of clinical course in cholecystectomized patients.