The Grocott-Gomori's (or Gömöri) methenamine silver stain, abbreviated GMS, is a popular staining method in histology. The stain was originally named after György Gömori, the Hungarian physician who developed the stain.

It is used widely as a screen for fungal organisms. Particularly useful in staining carbohydrates.

It can be used to identify the yeast-like fungus Pneumocystis jiroveci which causes a form of pneumonia called Pneumocystis pneumonia (PCP) or pneumocystosis.

The cell walls of these organisms are outlined by the brown to black stain.