The effect on the charring temperature of arsenic in blood with wall and platform atomisations of a number of matrix modifiers, such as cobalt, copper, nickel and palladium, has been studied. Based on this study, a nitric acid de-proteinisation-nickel matrix modification-graphite platform-in-furnace atomic absorption spectrometric method was developed for the determination of nanogram per millilitre levels of arsenic in whole blood samples after a systematic evaluation of the temperature programme of the atomiser. The method of standard additions is mandatory.