Information developed during recent years upon the toxicological actions of the fluid and solid polyethylene glycols is summarized. This information has been re-interpreted and supplemented. Evidence presented in this report confirms the earlier work indicating that acute oral toxicity, dermal toxicity, and irritating properties of the polyethylene glycols are very low. The safe rat dose of “Carbowax” 1500 is now known to be substantially greater than originally reported, and of “Carbowax” 4000, slightly greater.