Determination of trace amounts of iron and chromium in aluminium nitride was investigated using acid pressure decomposition method with a teflon pressure vessel and graphite-furnace atomic absorption spectrometry. The sample (0.5g) was decomposed with 6 ml of sulfuric acid (1+1) and 2 ml of nitric acid (1+1) in the vessel at 160°C for 5 h. The sample solution was diluted to 50 ml with water, and determined directly with graphite-furnace atomic absorption spectrometry. Background of molecular absorption of aluminium oxide (AlO) interfered in determination of iron with wavelength 248.3 nm. But iron was determined by selecting wavelength of 372.0 nm. The limits (10 σ) of determination of in the present method were 0.8 and 0.1 ppm for Fe and Cr, respectively.