Abstract: In this study, attempts were made to identify the presence microsporidian spores in pigs faeces from technified farms in order to improve the diagnosis of intestinal microsporidiosis. Since the knowledge about swine intestinal microsporidiosis as a zoonotic agent is unknown, the aim of this study was to determine the presence of spores in pigs in farms in Mexico, by using the trichrome blue and calcofluor techniques. The stool collection was made between the months of May to August 2008. Thin smears were made from individual undiluted stool samples, stained and visualized at 1000x in an epifluorescente microscope. Microsporidian spores were detected in 96 out of 120 fecal samples of finishing stage healthy pigs (80%). Mature spores were observed as red or pink oval to round structures with trichrome blue and with calcofluor, spores showed an intense blue bright, while incomplete or germinated spores showed a faint glow and a transparent appearance. The definitive diagnosis was the identification of the polar tube, which appeared as a pink or reddish belt in the middle of the spore. Present study reports for first time the presence of intestinal microsporidiosis in finishing stage swine farms of Nuevo Leon, Mexico in pigs in Nuevo Leon, Mexico.