Path analysis in General Control Theory Geza Meszena In: Modern trends in BioThermoKinetics. Ed. J-P. Mazat, S. Schuster, M. Rigoulet. Plenum Press, London, 1993, pp. 217-224 Summary A generalization of the Metabolic Control Theory is presented. It includes description of stable as well as optimal systems, and deals with the effect of an external change on the stable/optimal state. Path analysis is established in this framework. It gives a heuristic insight and makes a connection between the mathematical treatment and qualitative expectations about the behavior of the system. Control coefficients can be expressed as a sum of terms, each of them represents a path of propagation of the effect through the system. Application of this technic in metabolic control is presented as an example for this approach. Flux as well as concentration control coefficients are calculated.