Methodological problems of using fragmental descriptors for construction of QSAR/QSPR equations are considered, and the main achievements in this field are summarized and discussed. If a structure-property data set is sufficiently large to allow building statistically significant models, then any topological index can be replaced with a set of fragmental descriptors. Several examples of using the fragmental approach for predicting retention indices and the normal boiling points of organic compounds are considered. Advantages of using fragmental descriptors, namely a "transparency" and interpretability of QSAR/QSPR models, are exemplified.