Abstract. The present study used 3D data on neuronal morphology images to quantitatively characterize the phenotype of transgenic neurons. We calculated the multiscale fractal dimension (MFD) of reconstructed neuronal cells. It was shown that in a specific mouse mutant changes in the complexity of neuronal morphology correlate with changes in the MFD of dendrites of pyramidal neurons. Neurons in the mutant strain have lower peak fractal dimension compared with the wildtype, and a greater variety of the cell morphological phenotype.