Synchrotron powder diffraction data have been obtained and indexed for ferrous gluconate, a common supplement used for the treatment and prevention of iron-deficiency anemia. Ferrous gluconate (Fe(C6H11O7)2 · x H2O, Z = 4) crystallizes in a monoclinic cell (space group I2, #5) with lattice parameters a = 19.953 16(9) Å, b = 5.513 92(3) Å, c = 18.470 58(9) Å, and β = 111.3826(3)°. The pattern shows no evidence of impurity reflections.