Follicular lymphoma is one of the most immune-responsive cancers. The clonal tumor immunoglobulin expressed on the surface of malignant B cells, termed idiotype, has been used as a tumor-specific antigen in therapeutic vaccination strategies for follicular lymphoma and other B-cell malignancies. A number of phase 1 and phase 2 clinical trials have established the safety and immunogenicity of idiotype vaccine in follicular lymphoma. Three randomized, double-blind, controlled phase 3 clinical trials have recently been completed to definitively evaluate the clinical benefit of idiotype vaccine in follicular lymphoma. This review focuses on the results of these idiotype vaccine trials and discusses potential strategies to enhance the efficacy of vaccines in the future.