Cellulose acetate (CA) membranes are widely used for ultrafiltration applications. CA and poly (vinyl chloride) (PVC) blend membranes are prepared by using polar solvent of N, N-dimethylformamide (DMF) by phase inversion method. Polyethylene glycol (PEG 600) is used as polymeric additive in the casting solution. The effect of polymer composition and additive concentration on surface morphology, porosity are studied. The morphology of prepared membranes is found to have asymmetric structure with dense skin layer and porous sub-layer. Applications of these membranes are carried out for rejection and permeation of macromolecular proteins such as trypsin, pepsin, egg albumin, bovine serum albumin. On increasing the concentration of PVC and PEG 600, protein rejection decreases whereas permeate flux increases.CA/PVC/PEG (70/30/10 wt%) blend membrane shows the highest permeation flux of 211.1 lm(-2) h(-1) for trypsin.