Hydrogels embedded with networks of fully interconnected pores were prepared with microporous polylactide (PLA) molds obtained by extracting the polystyrene (PS) phase in melt-processed cocontinuous blends of PLA and PS. Quiescent annealing of the blends prior to the PS extraction allowed control over the average pore diameter from similar to 1 to similar to 500 mu m for the PLA molds. Solutions of agar or alginate were injected within the molds and gelled in situ. Porous gels were obtained by extracting the PLA molds and X-ray microtomography was employed to characterize their microstructure. Water removal/uptake cycles were fully reversible with very fast kinetics. Freeze-drying yielded ultraporous materials without modification of the macroscopic dimensions, and rehydration yielded back porous hydrogels. It was possible to scale up the technique by using extrusion and injection molding equipment. This versatile new method allows extensive control over the gels' porosity parameters and the use of various gel chemistries.