A method and apparatus for continuously casting a gradient or non-gradient electrophoretic gel slab includes reservoir cylinder blocks (1 and 2) which empty into nozzles (3) which deliver a gel solution onto a backing (4) riding between two belts (5 and 6), the belts sealed by platens (7) having UV transparent windows (8). As the gel solution is carried by the belts (5 and 6), it passes by a UV light source (9) which initiates polymerization of the gel. After polymerization, the gel slab is cut to a desired size.