Presently recommended methods for fractionation of airborne nickel dusts are laborious and time-consuming. A new method has been developed based on existing procedures of leaching nickel fractions from sample filters, and based on the principles of flow-injection analysis. A special sample filter holder has been constructed to be used in conjunction with the flow-injection system. In this system, soluble nickel compounds are extracted from the filter with ammonium citrate buffer, sulphidic nickel by peroxycitric acid, and metallic nickel by CuCl2/KCl. The final dissolution of the filter by HNO3/HCl results in the oxidic fraction. Endpoint determination of these fractions is performed by use of graphite-furnace atomic absorption spectrometry (GF-AAS). The analytical criteria of this method have been established, and the suitability of the method for application in the practice of industrial hygiene has been demonstrated.