Crystals of the non-collagenous C-terminal region (NC1) of type IV collagen have been obtained from human placenta. These crystals diffract to 2.0 A, and belong to space group P22(1)2(1), with cell dimensions a = 81 A, b = 158 A, c = 138 A, alpha = beta = gamma = 90 degrees. The crystals contain one hexamer in the asymmetric unit; they are very stable with respect to X-rays.