Vancomycin has come full circle in recent years. First used as an alternative to penicillin nearly a half-century ago, it was surpassed by methicillin and other semisynthetic penicillins that were regarded as less toxic. Paradoxically, the subsequent rise of methicillin-resistant Staphylococcus aureus (MRSA) has reestablished vancomycin as the primary antibiotic treatment for MRSA infections. With this in mind, what do we know about its pharmacodynamics that allows us to institute optimal monitoring strategies for this drug? Host Dr. Charles Turck welcomes Dr. Michael Rybak, associate dean for research, professor of pharmacy and medicine, and director of the Anti-Infective Research Laboratory at the Eugene Applebaum College of Pharmacy & Health Sciences at Wayne State University in Detroit.