The passage of Public Law 107-260, the Benign Brain Tumor Cancer Registries Amendment Act, in October 2002 has made the collection of all primary brain tumors a reality. However, at the first Consensus Conference on Brain Tumor Definition for Registration in 2002, and during the development of training materials for benign brain tumor collection, several issues were identified that were tabled for future discussion. These and other issues were addressed at the subsequent 2003 Consensus Conference on Cancer Registration of Brain and Central Nervous System Tumors, at which the Central Brain Tumor Registry of the United States facilitated a discussion among epidemiologists, neurosurgeons, and neuropathologists. Multidisciplinary consensus was reached on four points, for which the following recommendations were made: (1) amend the histology coding scheme for cysts and tumor-like lesions that currently have a code in the third edition of the International Classification of Disease for Oncology (ICDO), (2) collect data on all instances of specific cysts and tumor-like lesions that are located in brain and other CNS sites but currently lack ICDO codes, (3) establish a new ICDO topography site for skull base tumors for the brain and CNS, and (4) collect data on genetic syndromes in patients diagnosed with brain or CNS tumors. We view this conference as part of a continuing process. Because classification of primary intracranial and other CNS tumors is dynamic, and the registration and coding of these tumors will need to be periodically reviewed.