Polyesteramides, with different inherent viscosities, were synthesized from dimer acid, sebacic acid, ethylenediamine, and diethylene glycolamine. The effect of inherent viscosity of the polyesteramides on their thermal properties, such as melt viscosity, softening point, heat of fusion, glass-transition temperature, and low-temperature flexibility, was studied. The effect of the inherent viscosity on mechanical properties, such as tensile strength, elongation at break, and hardness, and on adhesion properties, such as lap shear strength and T-peel strength, was also investigated. The results show that melt viscosity, tensile strength, and elongation at break increase as the inherent viscosity increases, and that lap shear strength of the polyesteramides also increases with increasing inherent viscosity, whereas softening point, glass-transition temperature, and shore D hardness of the polyesteramides essentially do not change as the inherent viscosity increases within a certain range.