The design aspects of the 125 m high Salman Farsi (Ghir) arch-gravity dam in Iran, which is govermed by earthquake loads, are discussed. The dam is located in the seismically very active foothills of the Zagros Mountains. The methodology used for seismic shape optimization is-explained which includes the arrangement of the crest spillway and selection of the overall stiffness of the dam. The dam on massless foundation is analysed for the operating basis earthquake, taking into account compressibility of the reservoir and energy absorption at the reservoir bottom. Floor response spectra are given for the central crest spillway, where the maximum spectral accelerations for 5% damping reach values of up to 6 g compared to that of the ground motion of 0.7 g.