Liver and kidney damage associated with polytrauma, endotoxic shock/sepsis, and organ transplantation, are among the leading causes of the multiple organ failure. Development of novel sensitive biomarkers that detect early stages of liver and kidney injury is vital for the effective diagnostics and treatment of these life-threatening conditions. Several hepatic proteins, including Argininosuccinate Synthase (ASS) and sulfotransferases which were degraded in the liver and rapidly released into circulation during Ischemia/Reperfusion (I/R) injury were identified. Sensitivity and specificity of the newly developed sandwich ELISA assays for ASS and the sulfotransferase isoform SULT2A1 with the standard clinical liver and kidney tests Alanine Aminotransferase (ALT) and Aspartate Transaminase (AST) in various pre-clinical models of acute injury were compared. Ideally, biomarkers should employ biological substrates unique to the organ and, at the same time, provide information on injury mechanisms, a criterion that is used to distinguish biochemical markers from surrogate markers of injury since surrogate markers usually do not provide information on injury mechanisms. Argininosuccinate Synthase (ASS) is a link between urea cycle and Nitric Oxide (NO) synthesis which plays a major role in responses to ischemia, oxidative stress and toxins upon activation of inducible NO synthase in hepatocytes. Thus, ASS and SULT2A1 have superior characteristics over traditional biomarkers for liver and kidney health assessment in endotoxemia, I/R, chemical and drug-induced liver injury and may be of high potential value for clinical applications. (Prima V, Cao M, I Svetlov S, ASS and SULT2A1 are Novel and Sensitive Biomarkers of Acute Hepatic Injury-A Comparative Study in Animal Models)