The toxic nature of beryllium necessitates the use of a sensitive method for its detection. Present methods are not entirely satisfactory and the use of gas chromatography for the detection and determination of beryllium has been advocated. In the procedure described, beryllium is isolated by solvent extraction in the form of a volatile, thermally stable chelate with trifluoroacetylacetone, and is then determined by gas chromatography with an electron-capture detector. Results are presented for the determination of aqueous beryllium solutions and for beryllium contained in urine. Satisfactory results were obtained with both direct solvent extraction and solvent extraction after wet oxidation of the sample. The rate of excretion of beryllium by rats was measured by this method. The procedure is rapid, reliable and sensitive; the limit of detection is l ng ml–1.