Cancer vaccines are conceived as therapeutic tools, in contrast to the prophylactic vaccines that have resolved the problem of a number of infectious diseases in a highly cost-effective way. Over the last decade, anti-idiotype vaccines for human follicular lymphoma have started to come into their own. Whereas 10 years ago it was not even known whether patients could be immunized against an antigen of their own tumor, a phase III clinical trial based on this finding is now already underway. The rapidity of this development encourages the hope that active immunotherapy may become decisive in oncology sooner than expected. Many important results have already been achieved. These include evidence of vaccine-induced, tumor-specific humoral and cellular responses along with the first documented molecular remissions following vaccination. Crucial questions still awaiting an answer include: do Id vaccines actually cure at least a fraction of FL patients? What is the most effective vaccine formulation? Is it possible to reduce the workload involved in producing an effective Id vaccine?