Nanosized hexagonal wurtzite aluminum nitride (AlN) powders have been synthesized by the direct current (DC) are plasma method using mixed gas of ammonia and nitrogen (NH3-N-2) The growth of the crystals is affected by the thermal stability of their nitric surface, and the average size of the particles varies slightly according to reaction gas pressure. Fourier transform infrared (FT-IR) transmission measurements were carried out at room temperature on the nanosized powders in different mediums. The IR spectra show an intense and broad absorption peak at about 770 cm(-1) (epsilon(m)=2.36 of KBr) or 800 cm(-1) (epsilon(m)=1.0 Of in air) attributed to the Frohlich mode of the nanostructured ALN crystals. Some bulk modes also appear as shoulders or peaks in the spectra simultaneously.