A fast and reproducible purification procedure for rabbit skeletal muscle plasma membrane is described. Each step was monitored by determination of tetrodotoxin, ouabain and insulin receptors. A ouabain-sensitive K+-stimulated and a Ca2+-dependent phosphatases, probably identical to, respectively the (Na+-K+) and Ca2+-ATPases, were also evaluated. All plasma membrane receptors and the ouabain-sensitive activity accumulated in the lightest fraction separated by sucrose gradient centrifugation (peak at 18% sucrose; purification from crude homogenate, 30-fold).