Dissolution properties of Cu in molten Sn-Ag-Cu-Ni-Ge alloys have been investigated. In particular, the effect of the Ni content in the alloys on the dissolution properties has been examined. Moreover, the dissolution properties have been compared with those of Sn-Ag and Sn-Ag-Cu alloys. To investigate the dissolution rate of Cu in molten alloys, Cu wires were dipped in molten alloys heated at 250, 270 and 290°C. Dissolution thickness of Cu wire is proportional to dipping time regardless of alloy type. The dissolution rates of Cu follow the order Sn-Ag > Sn-Ag-Cu > Sn-Ag-Cu-Ni-Ge. In Sn-Ag-Cu-Ni-Ge alloys, the dissolution rate of Cu decreases with increasing the Ni content. In cases of Sn-Ag and Sn-Ag-Cu alloys, a thin Cu-Sn compounds layer forms at the interface between Cu and the alloy and dissolution of Cu does not proceed uniformly. On the contrary, a thick reaction layer, which consists of granular Cu-Ni-Sn compounds, forms at the interface between Cu and the Sn-Ag-Cu-Ni-Ge alloy. Since the reaction layer inhibits dissolution of Cu in molten alloy, the dissolution rate slows down and dissolution of Cu proceeds uniformly in the Sn-Ag-Cu-Ni-Ge alloys.