Objectives: Segmental liver hyperintensity can be observed in malignant biliary obstruction on diffusion weighted MRI (DW-MRI). We describe MRI findings associated with this sign and evaluate whether DW-MRI segmental hyperintensity has any relationship with serum alanine aminotransferase (ALT) levels. Methods: The DW-MRI T 1 weighted, T 2 weighted and gadolinium ethoxybenzyl diethylenetriamine pentaacetic acid (Gd-EOB-DTPA)-enhanced T 1 weighted images obtained in 21 patients with hepatic malignancy, who demonstrated biliary obstruction and segmental hyperintensity on DW-MRI (b50-750 s mm -2 ), were retrospectively reviewed by 2 readers blinded to clinical results. DW-MRI hyperintense liver segments were recorded as hypointense, isointense or hyperintense relative to normal liver on T 1 /T 2 weighted imaging. It was also noted whether contrast enhancement was similar to that observed in normal liver or diminished in the hepatocellular phase. The mean apparent diffusion coefficient (ADC) value (610 23 s mm -2 ) of DW-MRI hyperintense segments, normal liver and tumour were compared using Student's t-test. The frequency of MRI findings was corroborated with serum ALT levels, which reflect hepatocyte injury. Results: DW-MRI hyperintense segments frequently showed T 1 hyperintensity (10/21), T 2 hyperintensity (19/21) and/or diminished contrast enhancement (15/21). Tumours showed significantly lower mean ADC values than liver (1.23¡0.08 vs 1.43¡0.05; p50.013). Segments showing concomitant T 1 hyperintensity had lower mean ADC values than liver (1.30¡0.05 vs 1.43¡0.05; p50.023). The patients (8/10) with concomitant T 1 and DW-MRI segmental hyperintensity showed elevated ALT levels (p50.030, Fisher's exact test). Conclusion: Concomitantly high T 1 weighted and DW-MRI signal in liver segments was associated with lower ADC values and abnormal liver function tests, which could reflect underlying cellular swelling and damage.