Confocal scanning laser microscopy (CSLM) was investigated for the characterization of microfiltration membrane morphology. Three microfilration membranes were studied: a closed-cellular morphology (cellulose acetate membrane, Sartorius), a ＇lacy＇-like morphology (poly(vinylidene fluoride), Durapore, Millipore) and a cylindrical pores membrane (polycarbonate, Isopore, Millipore). Prior to visualization, the microporous membranes were mounted in immersion oil. Optical sections were taken at 1 mu m intervals. All membranes were observed on 10 mu m thickness from their surface, on both sides. CSLM was found useful to characterize microporous membrane morphologies and was compared to scanning electron microscopy (SEM) which views only surfaces.