End correctionsnfor the capillary flow of some polyethylenes have been determined as a function of shear rateGn. The end correction term increases slowly at first with logGn, but as the shear rate approaches the critical value at which the extruded filament becomes rough, bothnanddn/dlogGnincrease very rapidly. At the critical shear rate there is an abrupt decrease indn/dlogGn, and at higher shear ratesnincreases very slowly with logGn, with the slopedn/dlogGnbeing practically constant. All flow curves for a given polyethylene, obtained using capillaries of length to radius ratio ranging from zero to thirty, could be reduced to one single master curve by calculating effective shear stresses using the appropriate values of the end correction termn, with no apparent decrease in viscosity even for short capillaries in which the transit time of the polymer is very short.