Abstract: Methods and kits are provided for assessing radiation injury and exposure in a subject. The methods comprise measuring the levels of at least two (2) protein biomarkers from different biological pathways and correlating the levels with an assessment of radiation injury and exposure. Additional use of peripheral blood cell counts and serum enzyme biomarkers, evaluated in the early time frame after a suspected radiation exposure, and use of integrated multiple parameter triage tools to enhance radiation exposure discrimination and assessment are also provided. The information obtained from such methods can be used by a clinician to accurately assess the extent of radiation injury/exposure in the subject, and thus will provide a valuable tool for determining treatment protocols on a subject by subject basis.