Volatile compounds produced by 31 strains of pseudomonads and by reference strains of Pseudomonas fragi and Ps. fluorescens biotype 1 during growth on beef stored at 6 degrees C in air were analysed by gas chromatography-mass spectrometry of headspace gases. Compounds of major sensory significance were ethyl and methyl esters of C2-C8 fatty acids and sulphur-containing compounds which included methane- and isopropanethiols and their related sulphides and thioesters but not hydrogen sulphide. Ester production was mainly associated with growth of some, but not all, Ps. fragi and related meat strains but sulphur-containing compounds were produced by all but a single meat strain. A minority of other meat strains produced greater amounts of methyl ketones, secondary alcohols and unsaturated hydrocarbons believed to be of lipid origin.