1. The content of DNA, RNA and protein in the sporadin and cyst of the Gregarina blattarum were measured. 2. The amount of DNA, RNA and protein in a sporadin are 0.008 μg, 0.02 μg and 1.33 μg, and 0.053 μg, and 3.6μg in a cyst, respectively. 3. The content of these molecules increased with increase in size of the sporadin.