Clostridium difficile infection is a major cause of nosocomial disease in Western countries. The recent emergence of hypervirulent strains resistant to most antibiotics correlates with increasing disease incidence, severity and lethal outcomes. Current treatments rely on metronidazol and vancomycin, but the limited ability of these antibiotics to cure infection and prevent relapse highlights the need for new strategies. A better knowledge of the molecular mechanisms of the disease, the host immune response and identification of key virulence factors of Clostridium difficile now permits the development of new products specifically targeting the pathogen. Immune-based strategies relying on active vaccination or passive administration of antibody products are the focus of intense research and, today, the efficacy of monoclonal antibodies and of two vaccines are evaluated clinically. This review presents recent data, discusses the different strategies and highlights the challenges linked to the development of immunization strategies against this emerging threat.