In the title compound, {[Ga(2)(C(4)H(4)O(6))(2)(OH)(2)]·2H(2)O}(n), the Ga(III) atom is located on a twofold rotation axis and is six-coordinated by two O atoms from bridging hydroxide groups and four O atoms from two symmetry-related tartrate units in a slightly distorted octa-hedral environment. Each tartrate unit binds to two Ga(III) atoms as a bis-chelating bridging ligand by two pairs of hydroxide groups and an O atom of a carboxyl-ate group. The Ga(III) atoms are linked by two bridging hydroxide groups located on mirror planes. In this way a chain along the c axis is formed. Free water mol-ecules on mirror planes are located between the chains and hold them together through hydrogen-bonding inter-actions, with O⋯O distances in the range 2.509 (3)-3.179 (5) Å.