Oversimplified star-branched polymer systems were studied in Monte Carlo simulations. Model chains were based on a simple cubic lattice and each macromolecule consisted of 3 arms composed of 17 equal-length segments (total number of segments in a macromolecule equal to 49). The excluded volume and the attractive potential of nearest neighbors were also introduced into the model. The simulation algorithm was based on the entropy sampling (Monte Carlo) method (ESMC). The method allowed to determine directly the thermodynamic functions of the polymer chain at various temperatures and to describe the properties of the coil-to-globule transition (Figs. 2-6). Results of the ESMC method simulations were found to be consistent with those obtained by the classic Metropolis algorithm. The thermodynamic functions and the coil-to-globule transition were studied in relation to local stiffness of the chain.