This work presents the study of the effect of preliminary orientation on mechanical and structural behavior of semicrystalline polymers upon environmental intercrystallite crazing (EIC) for pristine and pre-oriented highdensity polyethylene (HDPE) by atomic force microscopy, wide-angle X-ray diffraction, birefringence, mechanical tests, pressure-driven liquid permeability, etc. Preliminary orientation of HDPE (PO) was performed in air at 100 degrees C. At moderate PO degrees (below 75%), PO HDPE samples preserve their ability to experience EIC. Finally, there exists a certain critical PO degree when the EIC process is found to be totally suppressed (100% for HDPE in n-heptane). The reasons behind the EIC suppression are primarily related to reduced sorptional capacity of the intercrystallite amorphous phase and to a partial fragmentation of crystalline lamellae. General prerequisite conditions providing the development of the EIC process for semicrystalline polymers are outlined.