Despite the importance of acetyl coenzyme A in many facets of metabolism and the availability of methods for estimation of its concentration, data for acetyl-CoA concentrations in plant tissues have been very scarce. A method using reversed phase HPLC for the quantitative estimation of acetyl-CoA was applied to a variety of plant tissues. In three different developing oilseeds the bulk acetyl-CoA concentration ranged from 5 to 25 nmoles/g fresh weight. In Arabidopsis thaliana leaves it was 5 nmoles/g fresh weight, and in Spinacia oleracea leaves 6.8 nmoles/g fresh weight. Immediate quenching of the harvested tissue in liquid nitrogen is needed to obtain high recoveries of acetyl-CoA.