and the ANRS CO12 CirVir GroupBaCKgRoUND aND aIMS: Porto-sinusoidal vascular liver disease (PSVD) is a rare cause of portal hypertension. PSVD is still often misdiagnosed as cirrhosis, emphasizing the need to improve PSVD diagnosis strategies. Data on liver stiffness measurement using transient elastography (TE-LSM) in PSVD are limited. The aim of this study was to evaluate the accuracy of TE-LSM to discriminate PSVD from cirrhosis in patients with signs of portal hypertension. appRoaCH aND ReSUltS: Retrospective multicenter study comparing TE-LSM in patients with PSVD, according to Vascular Liver Disease Interest Group criteria, with patients with compensated biopsy-proven cirrhosis associated with alcohol (n = 117), HCV infection (n = 110), or NAFLD (n = 46). All patients had at least one sign of portal hypertension among gastroesophageal varices, splenomegaly, portosystemic collaterals, history of ascites, or platelet count < 150 × 10 9 /L. The 77 patients with PSVD included in the test cohort had lower median TE-LSM (7.9 kPa) than the patients with alcohol-associated, HCV-related, and NAFLD-related cirrhosis (33.8, 18.2, and 33.6 kPa, respectively; P < 0.001). When compared with cirrhosis, a cutoff value of 10 kPa had a specificity of 97% for the diagnosis of PSVD with a 85% positive predictive value. A cutoff value of 20 kPa had a sensitivity of 94% for ruling out PSVD with a 97% negative predictive value. Of the patients, 94% were well-classified. Even better results were obtained in a validation cohort including 78 patients with PSVD. CoNClUSIoNS:This study including a total of 155 patients with PSVD and 273 patients with cirrhosis demonstrates that TE-LSM < 10 kPa strongly suggests PSVD in patients with signs of portal hypertension. Conversely, when TE-LSM is >20 kPa, PSVD is highly unlikely. (Hepatology 2021;74:364-378).