Abstract A very simple and inexpensive slab gel electrophoresis apparatus is described. This integral design reduces the leakage, cost, and size limitations frequently encountered in the construction and use of currently available apparatuses. An additional refinement eliminates the need for notching one member of the usual pair of glass plates used as gel slab molds. The apparatuses, in which linear, gradient, and two-dimensional gels have been routinely run, can be built in a wide variety of sizes and shapes for either analytical or preparative purposes. Several gel apparatuses can be clamped together and run simultaneously from a single power source. Ease of construction permits more than a dozen apparatuses of this design to be built in the space of a day or two by unskilled personnel.