- Most reliable - The two most commonly used are the Wheatley modification of the Gomori tissue trichrome stain and the iron-hematoxylin stain - Permanent stained smears are examined using oil immersion objectives (×600 for screening, ×1000 for final review of 300 or more oil immersion fields) - The permanent stained smear is the most important procedure performed to confirm the diagnosis of intestinal protozoan infections. - MODIFIED ACID-FAST: recommended for intestinal coccidia - MODIFIED TRICHROME: recommended for intestinal microsporidia