Diffraction experiments with 21 alloys from the system Cu-Sb were done by means of neutrons (1.19 Å) in transmission and by X-rays in reflection (Mo Kα, ţH-ţH goniometer). Corrections for neutron diffraction data are given and the RDF were calculated. Discussion of the nearest neighbours' distancerIand the coordination number z versus the concentration was done. With variation of the concentration the melts show compound formation, segregation tendency or statistical distribution of the atoms of both components. The quantitative subdivision of the melts with 15 up to 61 a/o Sb into two structural components shows that the melts with 44 a/o Sb contain up to 37 Mol% of Cu2Sb agglomerates.