The electron microscopic enzymo-cytochemistry is used to study on the organelles in both vegetative- and resting cells of Euplotes encysticus. The results revealed that: (1)The reaction particles of adenosine triposphatase (ATPase) was tightly confined to the membrane of food vacuoles in the vegetative cells, while in the resting cells they gathered around the pellicle. (2)In the vegetative cells, the localization of the reaction particles of acid phosphatase (ACPase) was in the food vacuoles or the autophagic vacuoles of different stages, while in the resting they formed the vacuolar or spherical bodies. (3)The reaction particles of succinate dehydrogenase scattered on the mitochondrial in the vegetative cells, though they could also be seen in the scattered mitochondria in the resting cells, its activity was weaker than that of the former. Thus it was supposed from the above results: (1) In most cases, the enzyme activities in the resting cells were weaker than in the vegetative cells. (2) The enzyme activity and localization might be different in different kinds of resting cells. (3) The resting cells could also have digestive duration, energy consumption and functional mitochondria.