While most virtual screening methods focus on identifying single molecules with a desired predicted property, working with analog series up front has the potential of readily identifying a whole family of compounds to be prioritized for additional computational analysis or tested experimentally for a richer and in-depth SAR analysis. In essence, ViSAS is a substructure search algorithm (see Figure ). However, the valid substructures to search are delimited before a direct comparison between queries and compounds in the database to search occurs. This allows the fragmentation of the databases to be computed in advance, thus reducing the substructure search to a text-matching problem. Moreover, the inherent hierarchical structure of analog series can be represented as scaffold networks and R-group tables allowing prompt local SAR analyses early on. >740 million unique molecules). For each core, an R-group table with the matching compounds can be computed.