Direct-acting antiviral (DAA) drugs exhibit considerable variability in mechanisms of metabolism and the extent to which they are substrates, inhibitors, or inducers of cytochrome P450 enzymes or P-glycoprotein and other drug transporters. Thus, potential drug-drug interactions with other commonly used therapies also vary, as do the effects of renal and hepatic impairment on DAA drug exposure. Drug-drug interaction profiles and use in cases of renal or hepatic impairment are reviewed for the DAAs simeprevir; sofosbuvir; ledipasvir; the fixed-dose combination regimen of paritaprevir, ritonavir, and ombitasvir plus dasabuvir; and the investigational drugs daclatasvir and asunaprevir. This article summarizes a presentation by Lucas Hill, PharmD, at the IAS-USA continuing education program held in Chicago, Illinois, in October 2014.