Darunavir, previously known as TMC-114, is a new protease inhibitor (PI) with a high affinity for the HIV-1 protease and strong ability to inhibit its action, even in mutated forms. Consequently, this drug is considered to have great intrinsic potency and a high genetic barrier. At the time of writing, data on the tolerability and safety of darunavir come mainly from studies of late rescue therapy (POWER, DUET), which have included more than 1,600 patients. Recent data, relating to shorter time periods, are also available from studies in early treatment-experienced patients (TITAN) and in treatment-naïve patients (ARTEMIS), increasing experience to a further 600 patients. Lastly, more than 4,000 patients who have received darunavir through the Expanded Access Program have allowed the drug's generally good safety and tolerability profile to be defined. In the studies performed to date, darunavir has been well tolerated, with a better profile than that of the PIs used in control groups in terms of adverse effects such as diarrhea, gastrointestinal tolerability and lipid alterations. Moreover, to date, no unexpected severe adverse effects have been reported.