Morphological sporulation characteristics of some of the chief potential allergenic molds found in the atmosphere of Santafé de Bogotá, were observed by scanning electron microscopy. The molds were fixed in pure acrolein vapors and OsO4, crystals and were dried in high vacuum to avoid damage to aerial structures and characteristic arrangements, as we have previously reported. SEM analysis revealed morphological variations of the studied molds and allowed detailed obseivationo f their surface ultrastructural characteristics, being of importance in the development of a structural, morphological and taxonomical study, by revealing structures, morphological characteristics and conidiogenetic details to provide better understanding of the process. Some structural details are difficult to observe by light microscope or phase-contrast microscope.