Preparative separations of creatine phosphokinase and bovine albumin are carried out by hollow fiber liquid chromatography. The hollow fibers used are poly(propylene), 240 mu m in diameter. They are uniformly coated with cross-linked poly(vinyl alcohol) and then reacted with the triazine dye Procion Blue MX-R. Experiments with these fibers show good protein separations, including those of the phosphokinase from the rabbit heart and the rabbit brain. Other experiments show that overloading can be successfully predicted. In terms of resolution at low sample loads, hollow fiber chromatography is currently inferior to analytical columns, though it is potentially superior for preparative separations.