Abstract Objective To assess the role of apparent diffusion coefficient (ADC) measured with diffusion-weighted imaging (DWI) in predicting and assessing response of hepatocellular carcinoma (HCC) to transarterial chemoembolization (TACE). Methods Thirty-six patients with cirrhosis and untreated HCC who underwent TACE and MRI within 3 months before and after TACE were assessed. MRI included DWI and contrast-enhanced T1-weighted imaging. Two observers measured ADC of HCCs and liver parenchyma on pre- and post-TACE MRIs and measured degree of tumor necrosis on subtracted post-contrast images on post-TACE MRI. Pre-, post-TACE tumor ADC, and changes in tumor ADC (ΔADC) were compared between lesions stratified by degree of tumor necrosis (measured on post-TACE MRI). Results Forty seven HCCs were evaluated (mean size 4.4cm, range 1.0–14.1cm). HCCs with poor and incomplete response to TACE (<50% necrosis on post-TACE MRI) had significantly lower pre-treatment ADC and lower post TACE ADC compared to HCCs with good/complete response (≥50% necrosis): ADC pre-TACE 1.35±0.42 vs. 1.64±0.39×10−3mm2/s (p=0.042); post-TACE ADC 1.34±0.36 vs. 1.92±0.47 (p=0.0008). There was no difference in ΔADC values. Conclusion This preliminary data suggests that pre-TACE tumor ADC can be used to predict HCC response to TACE.