Pure InP nanocrystals were synthesized in aqueous ammonia (potassium stearate. 0.01 mol.L-1) at 170degreesC for 12 h. The X-ray diffraction pattern was of the cubic phase with lattice constant a = 5.8523 +/- 5 x 10(-4) Angstrom. The secondary particles with 180 nm consisting of fine InP NCs with 15 nm in size were found from the transmission electron microscope images. The optimal reaction conditions were searched, and a possible reaction mechanism was discussed.