The aim of this study was to compare the antiketogenic effect of glycerol and propylene glycol after parturition. Two experiments were carried out on 36 Holstein cows. In each experiment there were 18 dairy cows receiving daily 300 ml of propylene glycol and either 500 or 1000 ml of glycerol during the first month of lactation. Blood was taken on weeks 1, 2, 3, and rumen fluid, on week 3 after parturition. A similar antiketogenic effect of 300 ml of propylene glycol and 500 ml of glycerol was observed. Although no negative effects of high doses of glycerol (1000 ml · d^–1) on metabolism, ruminal fermentation, or liver parenchyma were found, there were no additional positive effects over the 500 ml dose. The results indicate that glycerol is an appropriate alternative for cattle to prevent energy deficiency in the early lactation period, while increasing the daily glycerol dose from 500 to 1000 ml has no beneficial effect.