Lamina V-pyramidal neurons of regio precentralis agranularis in Golgi-Kopsch impregnated frontal series of the brains of four adult male rats were analyzed quantitatively in order to estimate the degree of individual variability. As parameters served the dendritic lengths, spine numbers and spine densities along the dendritic orders, within single dendritic fields and within the apical and basal parts of the dendritic tree or of the whole neuron. The significance of individual differences in these parameters between the animals was proven by the tests of Mann and Whitney or of Kruskal and Wallis. The variability turned out to be different in particular subdivisions of the neuron analyzed as well as for the parameter chosen. The basal single dendritic field showed a relative high degree of constancy in its data and the dendritic lengths were statistically more invariable than the spine values. The knowledge about high or less variable parameters in strictly selected neurons is of considerable importance for the planning of experiments followed by quantitative analyses of neurons. The application of the most suitable statistical method is also discussed.