[1,1,2,2- 2H]Ethanediol administered to Novikoff rat hepatomas was rapidly incorporated into glycol-derived neutral lipids and glycol phospholipids. The metabolic turnover rates of these diol-derived lipids and in particular of the diol phospholipids were at least an order of magnitude higher than those known for the corresponding glycerolipids. The data suggest that glycol phospholipids serve as precursors of the neutral glycol-derived lipids. Diol incorporation and diol lipid interconversions do not involve intermediary oxidation and reduction steps on the diol moiety. This was conclusively proven by mass spectrometry which showed that perdeuteration of the glycol moieties was retained in all instances.