A method is described for the determination of chromium in plant materials and soil samples by flame atomic absorption spectrometry. Factors influencing the sensitivity of the method for chromium and cationic interferences were investigated in air-acetylene and dinitrogen oxide-acetylene flames. Interferences that were pronounced in an air-acetylene flame were almost eliminated in a dinitrogen oxide-acetylene flame, so the latter was employed for the determination of chromium. Extraction of Cr₂O₇^2– into isobutyl methyl ketone was used to concentrate chromium from plant digests and soil extracts; Cr³⁺ in these solutions was efficiently oxidised by (NH₄)₂S₂O₈. Dry ashing followed by removal of silica was used for digestion of plants. Soil extracts (Na₂EDTA) should be ashed before the oxidation-extraction procedure. Total chromium in soil samples was determined without a pre-concentration procedure.