BACKGROUND: The human femur is the subsystem of the locomotor apparatus and has got four levels of its organization. This phenomenon is the result of the evolution of the locomotor apparatus, encompassing both constitutional and individual variability. The main aim of this investigation was to study the organization of the human femur as a system of collaborating anatomical structures and, on the basis of system analysis, to define the less stable parameters, whose reorganization can cause the exchange of the system's status. METHODS: Twenty-five (25) linear and non-linear (angle) parameters were, therefore, investigated by specially designed tool and caliper on a material of 166 macerated human femurs of adult individuals of both sexes. The absolute values were transformed into the relative one (1.0) by the meaning of the transverse diameter of the femoral diaphysis, and handled with current methods of descriptive statistical analysis. By the value of variance (q2), the results were distributed into four major classes. RESULTS: The belonging of each group to the class was subsequently estimated in grades. According to this method, the excerpt was distributed into four classes as well depending on the total grades. The Pearson's coefficient in each class was calculated between the relative values of the investigated parameters. Two generations of system parameters were subsequently defined and analyzed. CONCLUSION: This study has derived that the system meaning of each level of the femoral organization is related to the 'shaping effect' of femoral units' functions. Inasmuch as the angular parameters were most instable at this system, they were defined as morphological substrates of the individual variety.