PLGA microcapsule developed as a drug delivery system (slow release speed of medicines) material has, however, a problem, that is the initial burst release of medicine because of water penetrating into the PLGA capsules. To prevent water penetration, the fluorinated layer fort-nation on the PLGA surface by atmospheric pressure glow plasma was examined. We tried to use CF4/He plasma and C3F6/He plasma treatments for the formation. The C3F6/He plasma 7 times treated ones showed the worse initial burst release because this treatment destroyed the PLGA capsules by its excessive treatment time. On the contrary, since the C3F6/He plasma 5 times treatment could make the PLGA capsule surface enough hydrophobic, they had no initial burst release and the slow release speed. (c) 2005 Elsevier B.V. All rights reserved.