A radial-velocity curve based on fourteen high-dispersion coude' spectrograms of U Sgr has been constructed. The amplitude is 41,0 km , The velocity of the system is t3.38 + 0,19 km . There is a pronounced depression or "hump" of maximum depth about 3 km at phase 0.58 P. On ten of the spectrograms, interstellar lines of Na i or Ca ii were measured at an average velocity of -9.78 I 0,22 km . Spectra of two cluster members also showed sharp interstellar Na I lines at an average velocity of -9.78 I 0.33 km . The radial velocity of the cluster as a whole, found from 30-40 members by other observers, shows a remarkably close agreement with the systemic velocity of the Cepheid, thus greatly strengthening the case for its cluster membership.