The effects of nanoparticles (CdS) in semidilute polymer solution have been examined from a comparative study of the correlation functions of polymer and polymer-nanocomposite (NC) solutions at room temperature using dynamic light scattering (DLS) technique. NC has been synthesized chemically in the semidilute solution and the size of the nanoparticles has been determined from the UV-Vis absorbtion spectroscopy measurement. Our results show that the semidilute solution consists of two modes, namely, fast and slow modes having distinct values in their corresponding amplitudes and relaxation times. In the presence of nanoparticles, the eminent fast mode of the semidilute solution is found to smear out enhancing the slow mode. Quite interestingly, the temperature dependence study of both the solutions emerges the fact that above and below the room temperature, the polymer solution becomes more heterogeneous compare with the NC solution which is more homogeneous. (C) 2011 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 49: 377-383, 2011