Using the Golgi method, cells with intra-cortical axons in the visual cortex of young mice were classified according to defined geometrical axonal shapes. This study principally describes a computer technique and its application to the study of neuronal morphology. Neurons were converted in a sequence of three-coordinate points which were stored in digital form on magnetic tape. From the stored data and total real length in space of dendrites and axons was obtained and the results compared in two groups of mice raised under different conditions. Preliminary observations show short axonal lengths in mice raised in darkness. Using Eulerian coordinate transformations, reconstructions of individual neurons and of groups of several neurons and fibres were obtained by generating displays of different views after rotation around the horizontal axis. Reconstructed pictures were compared with their corresponding original drawings in order to describe particular aspects of cortical organization.