May Grunwald Giemsa (MGG) Staining


May Grunwald Giemsa stain is one of many stains under the Romanowsky staining procedure. It is a combination of two stains, May Grunwald stain and Giemsa stain. Like other Romanowsky stains, the principle is the same. It is used for bone marrow smear staining.


  • May Grunwald dye
  • Absolute methanol
  • Giemsa dye
  • Glycerol
  • Phosphate buffer pH 6.8


Preparation of May Grunwald stain

  1. Dissolve 0.3 g of May Grunwald dye in 100 mL absolute methanol in a 250 mL conical flask.
  2. Warm the mixture to 50°C in a water bath for a few hours and allow it to cool to room temperature.
  3. Stir the mixture on a magnetic stirrer and leave it stirring for 24 hours.
  4. Filter the mixture and stain is ready for use.

Preparation of Giemsa stain

  1. Add 1.0 g of Giemsa dye into 66 mL of glycerol and warm the mixture in a conical flask for 1-2 hours at 50°C.
  2. Cool the mixture to room temperature and add 66 mL of absolute methanol.
  3. Leave the mixture to dissolve for 2-3 days, mixing it at intervals.
  4. The stain is then ready for use after filtering.


  1. Fix BM smears in absolute methanol for 10-15 minutes.
  2. Prepare an equal volume of May Grunwald stain and phosphate buffer pH 6.8. Mix well and pour onto the slides to fully flood the slides. Stain for 10 minutes.
  3. Prepare a 1:10 dilution of Giemsa stain with phosphate buffer pH 6.8. Mix well.
  4. After 10 minutes of May Grunwald staining, pour away the May Grunwald stain off the slides.
  5. Then pour the Giemsa mixture onto the slides and stain for another 15 minutes.
  6. After 15 minutes, pour off stain and flush the slides with running tap water.
  7. Clean excess stain with kim wipes.
  8. Air dry the slides. *Hair dryer can be used to dry the slides but must be used at the lowest speed and no longer than 10 seconds each time.
  9. Place the long cover slip on the area of interest.
  10. The slide is now ready for examination.

Bone marrow smear x400 magnification.