In liver samples from NASH patients and murine NASH models, we identified an upregulation of TREM2 expression. TREM2 can be shedded from the surface of macrophages, making plasma TREM2 a potential non-invasive NASH biomarker candidate. Studying more than 200 obese patients we found that TREM2 levels were approximately doubled in NASH patients (NAS≥4) and found an area under the receiver operating characteristics curve (AUROC) of 0.92 and 0.83 in the derivation and validation cohorts, respectively. We further found that TREM2 is strongly associated to steatosis, ballooning and inflammation in the NASH patients. TREM2 displayed a higher AUROC than the FAST-score (AUROC=0.78) in our cohorts. Together the results point to TREM2 as a potential NASH biomarker or potential component of a composite NASH biomarker.