Organic biopolymers such as humic substances and polysaccharides account for the majority of freshwater NOM. Their role in natural systems is largely dependent upon their supramolecular microscopic structure which cannot be determined by bulk chemical measurements alone. Microscopic techniques were developed so as to permit the systematic observation of several colloidal-sized organic macromolecules with variable structures. This paper describes the characteristic structures of some reference compounds representative of the major organic components of natural waters. Polyacrylic acid, alginic acid and schizophyllan in addition to humic substances and polysaccharides isolated from natural freshwaters were examined by transmission electron microscopy (TEM) and atomic force microscopy (AFM). The techniques were optimized for the observation of the aquatic biopolymers. Colloidal organic matter isolated from natural freshwaters was also observed by TEM and AFM and compared with the standard images of colloidal organic matter.