The hypothesis of this research was that by stretching microfiltration or ultrafiltration membranes, their performance, in terms of flux and rejection, could be improved. Stretching a membrane was envisioned to stretch its pores, or change the aspect ration of the pores. It was thought that changing the aspect ratio could lead to improved flux (by increasing the pore area) while also improving the rejection of particles (by decreasing the length of the minor axis). The objective of this research was to study the effects of uniaxial stretching of microporous membranes (and thereby change the aspect ratio) on their performance (measured in terms of flux and particle rejection).