[en] Design and theoretical, as well as experimental, investigations of the integral parameters of carbon-uranium systems with a different number of cells have been carried out to ascertain the influence of heterogeneity and the possibility of using the theory of the material parameter when analysing results obtained for heterogeneous subcritical systems. The Galanin-Feinberg method has been used in the theoretical analysis of the heterogeneity effects. The experiments designed to study the influence of the number of cells on the parameters measured have been carried out on subcritical carbon-uranium systems with natural uranium using a reactor neutron beam. The number of cells varies from 9 to 81, the system height being 270 cm. The cadmium ratio Rsub(Cd)sup(28) and / has been measured. The parameter Rsub(Cd)sup(28), being the most sensitive one to changes in the dimensions of the system, remains unaffected with 25 cells or more. The results of the relative measurements of Rsub(Cd)sup(28) are in reasonable agreement with the data from the heterogeneity calculations