The Swiss Basel-Gasfabrik site represents an important Celtic settlement of urban character. Two species of intestinal parasites, Trichuris sp. and Ascaris sp., were identified in micromorphological thin sections from settlement pits. Species identification is complicated by taphonomic effects as well as the random representation of samples and cuts. Parasite eggs are encountered within and beyond original depository contexts due to water displacement and bioturbation. Our findings introduce micromorphology as a new means of paleoparasitological research which augments classical procedures. It captures parasite remains directly in their original microstratigraphic setting, thus providing information not to be obtained by classical flotation. Our observations are relevant for the selection of suitable sampling sites, sampling strategies, and methods of recovery and identification of paleoparasitological data in archeological sediments. They create new insights into site specific parasite dispersal and living conditions in the Late Iron Age.