Abstract: Light and electron microscopic observations of potassium hydroxide and culture smears of Pityrosporum yeasls were reported. There were many round chlamydospores and mycelia in the KOH smear, round and oval spores and mycelia of different leagths in the culture smear under light microscope. It was confirmed electronmicroscopically (SEM and TEM)that the round and oval spores were the different forms of the same fungus, but the length, diameter, morphology and internal and external structures of the long and short mycelia were different.