GUI Ant-Miner is a tool for extracting classification rules from data. It is an updated version of a data mining algorithm called Ant-Miner (Ant Colony-based Data Miner), which was proposed in 2002 by Parpinelli, Lopes and Freitas. GUI Ant-Miner differs from the original algorithm as follows: It has a friendly graphical user interface, makes possible the use of ant populations within the Ant Colony Optimization (ACO) concept, data input file is standardized with the well-known Weka system, and runs on virtually any operating system since it is written in Java. Aim of the software: This software is freely available for research and teaching (not a high-performance code). License: GPL. Programming language: Java. Comment: For further information concerning Ant-Miner and principles involved with it, please refer to: Parpinelli, R.S., Lopes, H.S., Freitas, A.A. ”Data mining with an ant colony optimization algorithm”. IEEE Transactions on Evolutionary Computation, special issue on Ant Colony Algorithms, v. 6, n. 4, p. 321-332, August, 2002.