Aim of research: To investigate the influence of laparoscopic cholecystectomy on the width of the common bile duct. Evaluate the correlation between the width of the common bile duct and the demographic, anthropometric and biochemical parameters. Research the possible connection of the anthropometric and biochemical parameters with the changes of the common bile duct width 6 months after surgery. Subjects and methods: The investigation was performed on 46 subjects with cholelithiasis (F/M 33/13, average age 56±14 years) and 50 healthy subjects (F/M 35/15; 55±13 years) of the control group with a low risk of choledocholithiasis. Preoperative and postoperative widths of the common bile duct were measured at the proximal, middle and distal segment with transabdominal ultrasonography 24 hours, 7 days, 3 months, 6 months and 4 years after laparoscopic cholecystectomy. The lower age limit of inclusion into the study was 18 and the upper 80 years of age. Results: Before surgery the subjects with cholelithiasis had a significantly wider common bile duct (p<0.05) with regard to the control group, and a positive correlation with the cholesterol level and alkaline phosphatase. Within the first 7 days of surgery the main bile duct significantly widened proximally and narrowed at the middle part. During the following months, a significant (p<0.05) dilatation of the preoperative bile duct occurred at the proximal and middle part, and at the distal part, of approximately 15-20% and 30-35% respectively, but not over the accepted upper limit of the normal result. Six months after surgery a significant increase of ALP and ALT values and a significant decrease of cholesterol levels were observed. Four years after surgery a significant decrease of cholesterol levels were observed. Conclusion: After laparoscopic cholecystectomy a dilatation of the common bile duct (p<0.05) at the proximal, middle and distal part occurred.