The structures of gels formed by a number of poly(oxyethylene)-poly(oxypropylene) diblock copolymers in aqueous solution have been investigated using small-angle X-ray scattering. Body-centered and face-centered cubic micellar phases were identified depending on the copolymer composition. The micellar radius in the gel is compared to that in dilute solution (obtained from static light scattering) and to predictions from scaling theory. The gel structures are compared to those reported previously for poly(oxyethylene)-poly(oxybutylene) diblocks in water.