Recent results of mass measurements of exotic heavy nuclei using Schottky mass spectrometry are reported. The investigated nuclei were produced and separated by the fragment separator FRS, injected, stored and cooled in the experimental storage ring ESR. Their masses were determined from the frequency analysis of the beam noise. In the present experiment the masses of more than 150 proton-rich nuclei in the mass region A ≃ 200 have been determined for the first time. Representative results are given for proton-separation energies and shell corrections. For some elements the proton drip line can be determined.