A new method based on atomic and structural contributions is proposed for estimating the critical volumes of organic liquids. The proposed method gives more accurate values compared with the methods of Lydersen, Joback and Somayajulu, the average absolute deviations being 2.3%, 3.2%, 3.1.% and 2.7% respectively for these four methods when tested against the experimental data for 279 organic liquids. The methods of Ambrose and Fedors recommended by the API technical data book for hydrocarbons and the AIChE data prediction manual for non-hydrocarbons gave overall average deviations of the same order as those for the Lydersen et al. method. The proposed constants can also be used to calculate the volume of liquids at the normal boiling point, with accuracies better than or comparable to those of the existing methods.