In the title compound, [Mg(C(3)H(4)O(3))(2)(H(2)O)(2)], the Mg(2+) cation is six-coordinated by four O atoms from two lactate anions and two aqua ligands, completing an MgO(6) distorted octa-hedral geometry. The complex mol-ecules are bridged by O-H⋯O hydrogen-bonding inter-actions into helical chains parallel to the a axis, which are linked by further O-H⋯O inter-actions, forming a three-dimensional supra-molecular architecture.