The expansion of protein solutions extrudates was measured at the exit of horizontal capillaries. Zein solutions of 25.0, 29.4, 35.7, 40.0 and 45.4 wt % in ethanol were used. Two capillaries, with a length over diameter ratio(L/D)of 12 and 73 were used in order to study the viscoelastic relaxation of zein solutions in the high shear region,103–104 sec−1.At the lower zein concentrations (25.0 and 29.4 wt %) no significant effect of the(L/D)ratio of the capillary was observed. However, at higher zein concentrations (35.7, 40.0, and 45.4 wt %) significant extrudate swell ratios (χ), up to 1.50 were observed, and the extrudate swell ratio depended on the(L/D)ratio of the capillary. ForL/D≃12,shear rate affected the extrudate swell ratio (χ) at the higher concentrations. For the long capillary(L/D≃73),the extrudate swell ratio (χ) of all the solutions approached the Newtonian valueχ≃1.12forRe<16,as expected from the behavior of recoverable shear strain(SR)reported earlier at lower shear rates. The existence of the two concentration regimes, in terms of extrudate swell ratios (χ), is consistent with the transition in rheological behavior of zein solutions previously reported by Menjivar and Rha. The expansion behavior of the extrudates has been explained in terms of the viscoelastic characteristic times of these solutions and the counteracting effect of shear on protein‐protein interactions and particle orientation.