X-ray powder diffraction data, unit-cell parameters, and space group for Ethyl (Z)-2-chloro-2-[2-(4-methoxyphenyl)hydrazin-1-ylidene]acetate, C11H13ClN2O3, are reported [a = 13.308(4) Å, b = 9.908(5) Å, c = 4.753(4) Å, α = 90°, β = 91.510(8)°, γ = 90°, unit-cell volume V = 626.64 Å3, Z = 2, ρcal = 1.361 g cm−3, and space group P21]. All measured lines were indexed and are consistent with the P21 space group. No detectable impurities were observed.