Histology, cytology and other related scientific disciplines study the microscopic anatomy of tissues and cells. In order to demonstrate a good visualization of tissue and cellular structures, the samples need to be properly stained. Sirius Red powder dye is an azo dye used principally in staining methods for collagen and amyloid. In histology, Sirius Red staining is used in various diagnostic domains to observe fibrosis levels in a lot of cases of inflammation induced by cancer, vascular or metabolic pathologies. In histology, Sirius Red is used to mark total collagen as well as differentiate between varying collagen types for evaluation of collagen distribution in tissues. In bright-field microscopy, collagen appears as bundles of pink to red fibers which get disturbed in pathological conditions.