The use of biological markers is developing in the field of liver transplant. Biomarkers are being studied in different contexts: 1) detection of tolerant patient; 2) recurrence of hepatitis C virus; 3) diagnosis and prognosis of liver cancers, and 4) diagnosis of infection. The immunological changes occurring in the transplant patient given their previous cirrhotic condition, the immunosuppression received, and possible intercurrent diagnoses (rejection, recurrence of hepatitis C virus…) highlight the importance of finding useful biomarkers in clinical practice to diagnose infection. After a review of the usefulness of biomarkers, we should perhaps add the serial determination of C-reactive protein in the immediate post-operative period, and later on procalcitonin, in the infection diagnosis algorithm. Although the determination of procalcitonin appears to be the most reliable biomarker in the differential diagnosis of sepsis and rejection, the studies carried out make it difficult to establish conclusions on its real clinical usefulness.