The blank holder gap is an effective way to control material flow. The effect of this gap on deep drawing of square cups with ETIAL-8 sheets was studied by the experimental approach. Different blank holder gaps ranging from 1 mm to 1.8 mm for 1 mm aluminum sheets were used in the experiments. The experimental implementation shows that a reasonable (optimized, controlled) value of blank holder gap has a great effect on the forming quality of the final part. Finally, a suitable blank holder gap for deep drawing of square cup for given tooling and material is proposed and the reasons of the failure modes are explained. (c) 2006 Elsevier Ltd. All rights reserved.