Small-angle neutron scattering experiments and density measurements were performed on dilute solutions of N,N'-dimethylpropyleneurea (DMPU) in heavy water in the mole fraction range 0.005(0.0025)-0.05 at 288.15, 298.15 and 313.15 K. From the experimental results values of the radius of gyration, second osmotic as well as second and third molal volume virial coefficients, and Kirkwood-Buff integrals were calculated. The results led to the conclusions that DMPU has a structure-making effect on water and the pairwise solute-solute interactions exhibit no temperature dependence and are less attractive in DMPU solutions than in N,N'-dimethylethyleneurea and tetramethylurea solutions.