Gel filtration on Sephadex LH‐20 in ethanol was shown to be a practical method for the single stage clean‐up of insecticide residues from grains. The advantage over previous column clean‐up procedures is that one set of conditions is applicable to most insecticides. The process is thought to be particularly applicable where routine screening procedures are operated. The clean‐up is adequate for thin‐layer chromatography. Copyright © 1968 John Wiley & Sons, Ltd