Alzheimer’s disease (AD) is an incurable neurodegenerative disease, which is accompanied by chronic inflammation. The immune system has an important role in the process of the disease. The deposition of amyloid β (Aβ) protein is a key pathological feature in Alzheimer’s disease. This article reviews immunotherapeutic strategies against AD. In murine models of AD, both active and passive immunization against Aβ induces a marked reduction in an amyloid brain burden and an improvement in cognitive functions. The findings from murine studies lead to clinical studies. One Phase II clinical trial of active immunization against Aβ was discontinued after 18 patients developed meningoencephalitis. After this lesson learned, new immunotherapeutic strategies, including both active and passive immunization, are investigated in clinical centers.