Hi Jung, I have installed OC4J stand-alone version 9.0.3 on Windows 2000 with JDK 1.3.1 All I did was unzip the ZIP file -- that I downloaded from Oracle's "Technet" site: http://technet.oracle.com And then navigated to the subdirectory ("j2ee\home") containing the "oc4j.jar" file -- on my machine this is: C:\oc4j\j2ee\home And then typed the following command: java -jar oc4j.jar -install It prompts you to enter a password for the "admin" user. And that's it! What did you do, and where did it fail for you, and what error messages did you get? Also, what version of OC4J are you trying to install and what JDK version are you using? Good Luck, Avi.