Objective: to compare the quality of residual colonic content tagging with 25 and 50 g of BAR-VIPS, the basе of which is barium sulfate (BaSO4), in preparing patients for virtual colonoscopy (VСS) and to evaluate the diagnostic efficiency of the method in both cases.Material and methods. The paper presents the results of VCS in 100 patients divided into two groups containing equal numbers (n = 50) according to the contrast medium dose (25 and 50 g). In each group, the quality of fecal tagging (FT) was compared by its presence and degree and by the presence and completeness of high-density artifacts for residual liquid and solid fragments separately. The reliability of the results of VCS versus fibrocolonoscopy was assessed in detecting additional colon tumors of three sizes (<6, 6-9, and ≥10 mm) in each group of patients. These results were used to calculate the diagnostic efficiency of VCS in each group.Results. The investigation showed significantly lower FT quality indicators in the patients using 25 g of BAR-VIPS than in those having 50 g of the same agent (p = 0.00001). Naturally to the quality of FT, all VCS information capability indices for all sizes of colonic tumors were lower in the 25-g group than those in 50g group.Conclusion. The option of preparing patients for VCS using residual colonic content tagging with 50 g of barium-containing BAR-VIPS has been found to have a significant advantage over that using 2 g of the same agent. This is shown in the better quality of FT and in the higher diagnostic efficiency of the method.