Introduction: Advances in drug therapy for multiple myeloma (MM) during the previous decade have improved survival outcomes; however, the disease remains incurable as patients eventually relapse or become refractory to all available therapies. Therefore, there is a clear need for more effective and well-tolerated treatments. Areas covered: We review preclinical and clinical data regarding the use of carfilzomib, a proteasome inhibitor that is structurally and mechanistically distinct from bortezomib, for the treatment of MM patients. Carfilzomib pharmacokinetics, pharmacodynamics, efficacy, safety and tolerability are summarized, based on Phase I/II trial data. Expert opinion: Carfilzomib represents a significant advance in the management of relapsed and/or refractory MM patients, including those intolerant or resistant to bortezomib. High response rates have been demonstrated with carfilzomib as a single agent or in combination with alkylating agents, immunomodulators and corticosteroids, even among patients who have failed multiple prior therapies. Carfilzomib also has significant potential in the frontline setting, with encouraging response and survival rates observed for combination regimens. Further evaluation of carfilzomib-containing regimens is ongoing in Phase III trials and investigator-sponsored studies, which include combinations with novel investigational agents. These findings will shape the future role of carfilzomib for MM patients across multiple settings.