A process is disclosed for preparing polyaspartic acid salts by treating polycondensates in an aqueous medium with bases. At least 0.7 equivalents of an alkaline metal and/or alkaline earth metal base per mole of the aspartic acid, aspartic acid imide and/or amide units contained in the polycondensates are used. The bases are added during 30 minutes to 20 hours to an aqueous suspension of the polycondensates of aspartic acid heated up to 40 to 140 °C, and the reaction mixture is optionally allowed to continue to react. These alkaline metal and/or alkaline earth metal salts of polyaspartic acids obtained by treating aspartic acid polycondensates in an aqueous medium with more than 1 equivalent of an alkaline metal and/or alkaline earth metal base for reducing the molar mass of polycondensates are used as additives for washing and cleaning agents.