This Report is a companion volume expanding on the material covered in ICRU Report 44, Tissue Substitutes in Radiation Dosimetry and Measurement. The new Report provides specific information on representative sets of tissues that illustrates the effects of tissue composition variation on the pertinent radiation interaction quantities. It includes photon, electron, proton and neutron interaction data for body tissues, covering the age interval from fetus to adult. Soft tissues, skeletal tissues and calculi are considered. Soft tissues include adipose tissues, brain, breast (including component tissues), heart, liver and muscles (skeletal), which includes the connective tissue, blood vessels, blood, lymph, etc., generally associated with striated muscle. Skeletal tissues and calculi include cortical bone, breast calcifications, cholesterol gallstones and various types of urinary (renal) stones. The first tabulation in the report provides elemental composition, mass and electron densities of the complete set of body tissues. This is followed with a tabulation (184 pages) of the photon, electron, proton, and neutron interaction data. These include mass attenuation coefficients, electron mass stopping powers, electron mass scattering powers, proton stopping powers and neutron kerma factors.