Enterococci are Gram-positive cocci with well-adapted mechanisms to colonize human and survive in inanimate environments over prolonged periods. They tend to affect patients who are elderly or debilitated, whose commensal flora has been altered by antimicrobial therapy, or whose epithelial or mucosal integrity has been disrupted. Although considered as low-virulent bacteria over the past years, enterococci have become one of the leading pathogens causing healthcare-associated infections in the recent years. They are common causes of nosocomial bacteremia associated with intravascular catheters, bacterial endocarditis on both native and prosthetic valves, urinary tract infections among patients who have received antibiotic treatment or urinary tract catheterization, post-operative intra-abdominal infections, etc. Enterococci are also common community pathogens, responsible for a minority of community acquired urinary tract infections. Enterococcus faecalis and Enterococcus faecium are two principal enterococcal species that are implicated in human diseases. Nowadays, increasing incidences of multidrug resistance in both species has made treating enterococcus infection a challenge. Three most worrisome types of resistance in enterococci are ampicillin resistance, high-level aminoglycoside resistance, and glycopeptide resistance, because these three types of antibiotics are the mainstay for treatment of enterococcal infections.