HIV protease (PR) is a key target for antiviral drugs, and HIV protease inhibitors (PIs) are a prime example of successful structure-based drug design. PIs show clear therapeutic benefits, but their efficacy can be compromised by poor bioavailabilitity, unwanted side effects, and most importantly, development of antiviral drug resistance. Therefore, the quest for novel, highly active compounds with improved resistance profiles, better pharmacokinetic properties, and fewer adverse effects continues. In particular, the problem of cross-resistance could be circumvented by identifying novel compounds that show different binding modes to HIV PR than the current clinical inhibitors.