The mechanical properties of agar-gelatin gels used to construct vessel mimicking phantoms for ultrasonic elasticity studies are investigated. Gels with varying compression moduli are made using a gelatin solution (8% by weight) with a variable amount of agar (1%-3% by weight). Carborundum particles were added as scattering material. The modulus is determined using a dynamic mechanical analyzer. The compression modulus of the gels is strongly dependent on the gelling temperature, age and the actual temperature of the samples. Compression moduli spanning a usable range for vascular phantom construction can be achieved by varying the amount of agar. Phantoms constructed from these gels are well suited to serve as a model for plaque containing vessels.