MayaChemTools is a growing collection of Perl scripts, modules, and classes to support a variety of computational drug discovery needs, such as manipulation and analysis of data, generation of two-dimensional (2D) fingerprints, similarity searching, and calculation of physicochemical properties. MayaChemTools provides command line scripts for the following tasks: manipulation and analysis of data in SD, CSV/TSV, sequence/alignments, and PDB files; calculation of a key set of physicochemical properties, such as molecular weight, hydrogen bond donors and acceptors, logP, and topological polar surface area; generation of 2D fingerprints corresponding to atom neighborhoods, atom types, E-state indices, extended connectivity, MACCS keys, path lengths, topological atom pairs, topological atom triplets, topological atom torsions, topological pharmacophore atom pairs, and topological pharmacophore atom triplets; similarity searching and calculation of similarity matrices using available 2D fingerprints; listing properties of elements in the periodic table, amino acids, and nucleic acids; and exporting data from relational databases. An extensive set of modules and classes are also available for custom development. MayaChemTools is freely available online at www.MayaChemTools.org , under the terms of the GNU LGPL, as published by the Free Software Foundation.