BACKGROUND: A small remnant liver volume is an important risk factor for posthepatectomy liver failure. ImageJ and OsiriX((R)) are both free, open-source image processing software packages. The aim of the present study was to compare ImageJ and OsiriX((R)) in performing prospective computed tomography (CT) volumetric analysis of the liver on a personal computer (PC) in patients undergoing major liver resection. METHODS: Patients scheduled for a right hemihepatectomy were eligible for inclusion. Two surgeons and one surgical trainee measured volumes of total liver, tumor, and future resection specimen prospectively with ImageJ and OsiriX((R)). A radiologist also measured these volumes with CT scanner-linked Aquarius iNtuition((R)) software. Resection volumes were compared with the actual weights of the liver specimens removed during surgery, and differences between the measured liver volumes were analyzed. RESULTS: A total of 15 patients (8 men, 7 women) with a median age of 63 years (48-79 years) were included. There was a significant correlation between the measured weights of resection specimens and the volumes calculated prospectively with ImageJ and OsiriX((R)) (r = 0.89; r = 0.83, respectively). There was also a significant correlation between the volumes measured with radiological software iNtuition((R)) and the volumes measured with ImageJ and OsiriX((R)) (r = 0.93; r = 0.95, respectively). CONCLUSIONS: There were no major differences in total liver volumes, resection volumes, or tumour volumes for these three software packages. Prospective hepatic CT volumetry with ImageJ or OsiriX((R)) is reliable and can be accurately used on a PC by nonradiologists. ImageJ and OsiriX((R)) yield results comparable to the radiological software iNtuition((R)).