The deproteinised sample (150 microliters) is 'injected' into a continuously flowing stream of deionised water which is pumped, via a capillary tube, to the nebuliser of an atomic absorption spectrophotometer. Analytical readout is obtained, in the form of transient peaks, 6 s after sample injection. Before injection traces of haemoglobin are removed from the serum by treatment with trichloroacetic acid-ascorbate solution. This protein precipitant facilitates rapid removal of haemoglobin bound iron without the need for heating. After centrifugation the supernatant solution is introduced into the flowing stream by use of a novel inexpensive 'injector'. Analytical recovery and precision are good, and results compare well with those obtained by a standard AutoAnalyzer procedure.