Orcein stain is a staining technique used for the visualization of hepatitis B surface antigens (HBsAg), elastic fibers and copper-bound proteins.

Viral particles present inside host cells are called viral inclusion bodies. With orcein staining, HBsAg antigens appear as irregular aggregates in the cytoplasm of host cells.

Copper-related proteins are present in large quantities in cells during diseases such as Wilson's disease or certain forms of cirrhosis. These proteins can be visualized through orcein stain.

Orcein stain can be used on formaldehyde and paraffin sections and frozen sections.

Here are some examples of stains obtained with orcein stain: