To determine the measurement reproducibility of IVIM (intravoxel incoherent motion) diffusion parameters, ADC (apparent diffusion coefficient) _(0,500) and ADC_total of large Hepatocellular carcinoma.Twenty-seven patients (31 lesions) with primary HCC underwent MRI examinations including two repeat IVIM DWI sequences with 12 b values (0, 10, 20, 30, 40, 50, 70, 100, 200, 300, 500, 800 s/mm2). Regions of interest (ROIs) were drawn within the outer border 1 mm from peripheral margin of the selected HCC(Figure) to derive intravoxel incoherent motion (IVIM) parameters D, D*, and PF, ADC_(0,500) and ADC_total (all 12 b values) by a Bayesian method. Short-term measurement reproducibility of IVIM parameters and ADCs were assessed by measuring interclass correlation coefficients (ICCs), coefficient of variation (CV) and Bland–Altman limits of agreements (BA-LA).The intra- and interobserver ICCs were good for HCC except for D⃰ value ranging from 0.829 to 0.946. The reproducibility was good For D and ADC_total (CV 15.5％, 14.4％ and 13.1％, 10.8％ respectively) and was poor for D⃰ and PF (CV values were >30%) for both first and second DWI series, thus suggesting less variability of D and ADC_total. The strongest 95 % Bland–Altman limits for agreements (BA-LA) of short-term measurement reproducibility was noted for ADC_total (-15.9％ to 18.2％), followed by D (-21.0％ to 30.7％) and ADC_(0,500) (-37.6％ to 46.7％). Very wide 95 % confidence limits were observed for D⃰ (-115.1% to 128.7%) and PF(−96.7% to 98.0 %). The reproducibility of IVIM Parameters and ADCs for lesions 50 mm or larger in diameter was better than that for lesions smaller than 50 mm.D* and PF are perfusion-sensitive parameters calculated from low b values at which blood magnetization dominates the signal attenuation, they are potentially more sensitive to measurement uncertainty resulting from capillary perfusion and signal to noise variations, thus D⃰ and PF show considerable measurement variability^[1,2]. D and ADC_total may be potentially more meaningful quantitative parameters in clinical practice and the larger lesion is preferable when applying ADCs from DW imaging to the monitoring of treatment response of hepatic disease, as using more b values gives more accurate ADC value, especially where the likely ADC values are not kown a priori, at higher b values, pseudodiffusion account for only a small proportion of the measured signal in each imaging voxel and may tease out the effects of microcapillary perfusion^[3]. The larger lesion is preferable when applying ADCs from DW imaging to the monitoring of treatment response of hepatic disease. Yeon Kim Set al^[4] turned out that ADC measurement of malignant hepatic tumors tended to be more reproducible for larger rather than smaller lesions, they pointed out that this may have resulted from the partial volume averaging effect, which probably more severely affected the ADC measurement of smaller lesions.