When MULTAN-78 or MULTAN-80 is empoyed to solve a crystal structure, usually only partial structure can be found at first. The remaining atoms are then located by the weighted Fourier synthesis. In this paper, however, two examples are given to show that, when most of the atomic positions are already known, especially when the known part contains heavy atoms, the unweighted Fourier synthesis can give better results than that from the weighted Fourier synthesis.MULTAN-80 has been modified to calculate also the unweighted Fourier synthesis.