Growth of single crystal beta carbon nitride (beta-C3N4) nanorods (see Figure) has been achieved for the first time through thermal annealing of nanosized carbon nitrides induced by high-energy ball milling under a streaming flow of NH3. Most of the nanorods grow along the [001] direction, and the surfaces are defined by (011) and (010) specific crystallographic planes. A possible growth mechanism of the beta-C3N4 nanorods is discussed.