Vancomycin resistance in Gram-positive cocci, as exemplified by Enterococcus and Staphylococcus aureus, has become a significant clinical challenge. The first vancomycin-resistant Enterococcus isolates were reported in Europe in 1988 and later in the United States. Vancomycin-resistant enterococci (VRE) have spread rapidly and are now found in hospitals worldwide. This review discusses the mode of action of vancomycin and the mechanisms of resistance, particularly the VanA type, which is mediated by transposon Tn1546. The VanA system replaces the D-Ala-D-Ala dipeptide in peptidoglycan precursors with D-Ala-D-Lac, reducing vancomycin binding. Other resistance mechanisms include VanC, VanB, VanD, VanE, and VanG types, each involving different enzymatic modifications or removal of susceptible targets. VanA is the most common type in enterococci and the only one in Staphylococcus aureus. VanC is intrinsic to certain enterococci. VanB and VanD involve similar mechanisms but differ in regulation. VanD is constitutive and not transferable. VanE and VanG are associated with low-level resistance. The spread of resistance is facilitated by plasmid-mediated transfer of resistance genes. In Staphylococcus aureus, vanA genes have been transferred from enterococci, leading to vancomycin-resistant strains. The genetic basis of resistance involves complex regulatory systems, such as the VanS-VanR two-component system. The emergence of vancomycin-resistant strains poses a significant threat to treatment options for infections caused by Gram-positive bacteria. The spread of resistance genes among bacteria, including between Gram-positive and Gram-negative species, is a major concern. Understanding the genetic and biochemical mechanisms of resistance is crucial for developing effective strategies to combat vancomycin resistance.Vancomycin resistance in Gram-positive cocci, as exemplified by Enterococcus and Staphylococcus aureus, has become a significant clinical challenge. The first vancomycin-resistant Enterococcus isolates were reported in Europe in 1988 and later in the United States. Vancomycin-resistant enterococci (VRE) have spread rapidly and are now found in hospitals worldwide. This review discusses the mode of action of vancomycin and the mechanisms of resistance, particularly the VanA type, which is mediated by transposon Tn1546. The VanA system replaces the D-Ala-D-Ala dipeptide in peptidoglycan precursors with D-Ala-D-Lac, reducing vancomycin binding. Other resistance mechanisms include VanC, VanB, VanD, VanE, and VanG types, each involving different enzymatic modifications or removal of susceptible targets. VanA is the most common type in enterococci and the only one in Staphylococcus aureus. VanC is intrinsic to certain enterococci. VanB and VanD involve similar mechanisms but differ in regulation. VanD is constitutive and not transferable. VanE and VanG are associated with low-level resistance. The spread of resistance is facilitated by plasmid-mediated transfer of resistance genes. In Staphylococcus aureus, vanA genes have been transferred from enterococci, leading to vancomycin-resistant strains. The genetic basis of resistance involves complex regulatory systems, such as the VanS-VanR two-component system. The emergence of vancomycin-resistant strains poses a significant threat to treatment options for infections caused by Gram-positive bacteria. The spread of resistance genes among bacteria, including between Gram-positive and Gram-negative species, is a major concern. Understanding the genetic and biochemical mechanisms of resistance is crucial for developing effective strategies to combat vancomycin resistance.