In order to analyze the structural organization of complex axonal arbors reconstructed from histological serial sections, and to investigate the functional implications of their geometrical properties, we developed software providing the following facilities: (1) direct importation of data files generated by a commercially available 3-D light-microscopic reconstruction system, including routine procedures for identification and correction of data acquisition errors; (2) real-time 3-D rotations of the arbors in the stack of serial sections; (3) multiple interactive display modes; (4) possibility of modifying diameter and/or connectivity of different branches; (5) simulation of the invasion of the arbor by a single action potential initiated at any chosen point, and visualization of spatio-temporal profiles of activation; (6) extraction of quantitative data converted to standard file formats compatible with available mathematical software. All these tools can be applied to single or multiple axons, individually or simultaneously. The software, called Maxsim, is a highly flexible C-written program running on graphical workstations using the UNIX operating system and X-Window environment.