A system of calculating relative mobilities of mutant hemoglobins and globin chains in four methods of zone electrophoresis is described. In electrophoresis on cellulose acetate, TEB buffer, pH 8.5, mobilities are calculated as ratios of the mobility of simultaneously analyzed Hb C. In electrophoresis on citrate agar, pH 6.0, anodic mobilities are also related to Hb C, cathodic ones to Hb F. In globin electrophoresis in urea 2-mercaptoethanol buffers, pH 6.0 and 8.9, mobilities of the mutant globin chains are calculated in relation to the mobilities of normal alpha and beta chains. These calculations provide objective comparisons of mobilities of hemoglobins, including those analyzed at different times. The combined data permit recognition of many mutant hemoglobins.