This study focuses on the gene expression of CYP2B6, CYP3A4, and ABCB1 transporters in patients with HIV, HCV, and HIV/HCV co-infection, aiming to assess their potential association with the choice of therapy, patohistological and clinical parameters of liver damage such as the stage of liver fibrosis, serum levels of ALT and AST, as well as the grade of liver inflammation and other available biochemical parameters. The gene discussed is ABCB1; the disease is Hepatic fibrosis.