Background and Study Aims: The accuracy of transurethral bladder catheter pressure in reflecting intra-abdominal pressure is well defined in experimental studies and case reports but not in controlled clinical trials. Patients and Methods: We compared bladder pressure with insufflator pressure during laparoscopic cholecystectomy in 40 patients. Measurements were made at four pressure levels of the insufflator: 0, 5, 10 and 15 mmHg. Results: When the insufflator displayed 0, 5, 10, and 15 mmHg (0, 6.8, 13.6 and 20.4 cmH2O), and the mean bladder pressures measured 2.5 ± 1.4, 7.3 ± 1.5, 12.9 ± 1.6 and 19.7 ± 1.5 cmH2O, respectively. The two measurements correlated well with each other (r = 0.973, P < 0.0001). Conclusion: We concluded that bladder pressure measured by transurethral catheter was equal to insufflator pressure during laparoscopy, and that this was a valid indicator of intra-abdominal pressure.