A program for the interactive selection of potential starting materials given a desired target molecule is described. The program uses hierarchical search to rapidly select candidates from a large starting material library and contains a function to evaluate the appropriateness of the functionality of the starting material. The user can specify restrictions on features such as the number of atoms in the starting material, price limitations, chirality, and whether to use superstructure or substructure searching. Several examples of the results of the program are presented.