Leaf wax alkanes were extracted from 41 genera and 58 species belonging to the Umbelliferae, from 35 genera and 61 species belonging to the Cruciferae and from 32 genera and 78 species belonging to the Leguminosae. n-Alkane composition was determined by GC and GC-MS. All families were characterized by the presence of C29 and C31; however, in the Umbelliferae, the C29 content was greater and in the Cruciferae, it was equal and in the Leguminosae, it was lower than that of C31. The data matrix of the n-alkane percentages and total content was used to calculate for each family a cluster analysis. The results obtained confirmed the usefulness of leaf wax alkanes as chemotaxonomic characters at the familial, subfamilial and tribal levels.