Hepatocellular carcinoma (HCC) and liver metastases are an increasing problem worldwide. Non-invasive methods for understanding of HCC growth mechanisms are highly desirable. A biexponential model for analysis of non-invasive diffusion-weighted 1 H magnetic resonance imaging (MRI) provides important information about neoplastic transformation in capillary liver tissue perfusion and water molecular diffusion. Fast and slow components of water apparent diffusion coefficient (ADC) were separated in the normal rat liver, intrahepatic, and subcutaneous HCCs. MRI was acquired with a Varian 9.4 T horizontal bore system. The fast component of ADC (ADC fast ), which contributes 38% to total signal in the intrahepatic HCC, was significantly lower compared to normal liver value, while the slow component of ADC did not differ in liver, intrahepatic, and subcutaneous HCCs. A decrease in ADC fast may be caused by restricted perfusion in abnormal tumor microvessels. Thus, a reported earlier decrease in ADC in HCC compared to normal liver was mostly due to a decreased in tumor perfusion rather than a decrease in water diffusion. Subcutaneous HCC showed a very limited vasculature development, which makes the tumor perfusion extremely poor and hypoxic. Simultaneous monitoring of water ADC changes in orthotopic and subcutaneous HCCs may be useful, but a possibility of location-based physiological and metabolic differences must be recognized. Keywords: hepatocellular carcinoma, 1 H-MRI, apparent diffusion coefficient, perfusion, tumor location.