Structure-activity relationships study was performed for a series of Schiff bases hydroxysemicarbazide as potential antitumor agents by using the electronic-topological method combined with neural networks (ETM-NN). Data for the approach were obtained from conformational and quantum-chemical calculations and arranged first as matrices called electronic-topological matrices of contiguity, by one for each compound. Then specific molecular fragments were found for active compounds ('activity features') from the ETM application. After this, a system of prognosis was developed as the result of training the Kohonen self-organizing maps (SOM) by the most significant fragments. (c) 2005 Elsevier Inc. All rights reserved.