Rhodanine stain is used in histology to identify copper deposits. The reaction utilizes the property of copper to bind with high affinity to protein copper deposits in tissue sections.

Excess copper deposits are found in the cytoplasmic proteins of cells in many liver-related pathologies such as chronic biliary obstruction and chronic hepatitis. Quantification after rhodamine stain on tissue sections is the most commonly used method to highlight the presence of abnormal copper deposits.

Rhodamine stain is mainly used in the diagnosis of Wilson's disease for its sensitivity gain compared to the rubeanic acid test. This disease causes an excess of copper that causes liver damage that can lead to acute hepatitis and advanced cirrhosis. Excess copper in cases of Wilson's disease can also be found in the brain and in the cornea of the eyes.