High-strength　ultrafine　eutectic-dendrite　composites　were　produced　from　arc-melted　ingots　of　a　novel　Ni-Hf　alloy　system.　The　composites　are　composed　of　micron-scale　dendritic　phases　(Ni5Hf　intermetallic　phase　or　Ni　solid　solution)　and　an　ultrafine　lamellar　eutectic　matrix　(Ni5Hf　+　fcc-Ni).　The　optimization　of　the　Ni-Hf　alloy　composition　is　performed　from　the　viewpoint　of　both　high　strength　and　ductility.　The　strongest　Ni90Hf10　has　an　ultrafine　lamellar　eutectic　structure　and　exhibits　a　high　strength　of　3.56　GPa　and　a　plastic　deformation　of　34%　under　compression.　In　particular,　the　material＇s　plasticity　can　be　monotonically　improved　by　reinforcing　the　ductile　dendritic　phases　in　the　eutectic　matrix.　The　high　strength　and　ductility　values　can　be　achieved　without　using　the　injection　mould　casting　or　rapid　solidification　procedure.　The　microstructure　property　relationship　of　these　ultrafine-structured　composites　is　also　discussed　here.