In　this　paper,　the　hybrid　implicit-explicit　finite-difference　tine-domain　(HIE-FDTD)　algorithin　for　a　two-dimensional　(2D)　TE　wave　is　extended　to　a　full　three-dimensional　(3D)　wave.　The　weakly　conditional　stability　is　verified　by　numerical　simulation　results.　Numerical　formulations　of　the　3D　HIE-FDTD　method　are　presented　and　simulation　results　are　compared　to　those　using　the　conventional　3D　finite-difference　time-domain　method.　High　computation　efficiency　is　obtained　by　introducing　an　unequal　space　increment　in　different　dimensions　in　the　HIE-FDTD　method.　(c)　2006　Wiley　Periodicals,　Inc.