The generalized optimized random-phase approximation (ORPA) for binary mixtures is applied to an investigation of the structure of liquid Al-Ge alloys. We show that the liquid structure and its variation with composition is strongly influenced by medium- and long-range interatomic forces. The short-range structure is characterized by almost concentration independent coordination numbers for alloys containing up to 40 atomic percent Ge. At about 50 atomic percent Ge the coordination changes to smaller coordination numbers characteristic for liquid Ge. The long-range structure is rather complex and is determined by the interplay of three different length scales: the effective hard-core diameters of the two atomic species and the Friedel wavelength of the oscillations in the interatomic potentials.