The experiment was conducted at Gialam, Hanoi, in summer rice. Results showed that number of eggs of the Panicle Rice Mite (PRM) on different rice cultivars was different, resulting in different degrees of damage. Generally, at 4 developmental stage of the rice plant, the number of PRM in different leaf was different. At the shooting stage, the highest number of the mite and egg concentrated at leaf number 2. Then at panicle initiation stage, the highest number of the mite and eggs was at the leaf number 3. At the flowering stage, the highest number was at the leaf number 4, at this stage some mite occupied on young panicle. At milky stage (2 week after flowering) the highest number of the mite and eggs was at the leaf number 3. On the panicle the number of mite and eggs was increased. The dimension of the mite's damage was only obvious direct before flowering on the leaf number 2 (0.3 - 0.4 cm long). At flowering stage the symptoms of damage were clearly seen at the. leaf number 1 and 2. At milky stage the largest damage was seen at the leaf number 2.(1.18 - 1.2 cm long).