Recent molecular dynamics and transmission electron microscopy results on irradiated metallic materials are reviewed, with an emphasis on defect production in the displacement cascade and the fluence- and temperature-dependent accumulation of defect clusters. Materials analyzed include Fe, V, Cu, austenitic stainless steel, V4%Cr4%Ti, and ferritic/martensitic steel. Intrinsic differences between the defect accumulation behavior of body centered cubic (BCC) and face centered cubic (FCC) metals are highlighted. Results on the temperature-dependent vacancy cluster density of Cu are discussed in terms of thermal stability of stacking fault tetrahedra (SFTs). Finally, recent results on deformation behavior of irradiated, quenched, and deformed metals are discussed, with particular emphasis on flow localization mechanisms (e.g., dislocation channeling), and experimental and molecular dynamics studies of the detailed dislocation-defect cluster interactions.