Hierarchical single-crystalline AIN nanocombs were self-assembled through a chemical-vapor transport and condensation process. The wurtzite AIN nanoarchitectures are composed of core stems along the <0001> direction and comb-like nanotips growing perpendicularly out from both sides of the stems along the <0 (1) over bar 10> direction (see Figure). Low-threshold field emission could be obtained from the nanostructures, with potential applications in field-emission displays and microvacuum tubes for microwave amplifiers.