Victims of radiological terrorism events require prompt diagnosis and treatment of medical and surgical conditions as well as conditions related to radiation exposure. Hospital emergency personnel should triage victims using traditional medical and trauma criteria. Radiation dose can be estimated early post-event using rapid-sort, automated biodosimetry and clinical parameters such as the clinical history, the time to emesis (TE), and lymphocyte depletion kinetics. For TE < 2 h, the effective whole-body dose is at least 3 Gy. If TE < 1 h, the whole-body dose most probably exceeds 4 Gy. Lymphocyte depletion follows dose-dependent, first order kinetics after high-level gamma and criticality incidents. Patient radiation dose can be estimated very effectively from the medical history, serial lymphocyte counts, and TE, and subsequently confirmed with chromosome-aberration bioassay, the current gold standard. These data are effectively analyzed using the Armed Forces Radiobiology Research Institute Biodosimetry Assessment Tool. The medical management of patients with acute, moderate to severe radiation exposure (effective whole-body dose >3 Gy) should emphasize the rapid administration of colony stimulating factors. All of these compounds decrease the duration of radiation-induced neutropenia and stimulate neutrophil recovery, albeit with some variability, in patients who have received myelotoxic chemotherapy, and all have demonstrated benefit in irradiated animals. For those patients developing febrile radiation-induced neutropenia, adherence to the current Infectious Diseases Society of America guidelines for high-risk neutropenia is recommended.