From what I remember you'll have to use a 9i client to connect to a 10g database. The 8i client never worked for me connecting to 10g. If you do, just install in different homes and you should be ok. Jeremy P Consider the environment. Please don't print this e-mail unless you really need to. From: oracle-l-bounce@xxxxxxxxxxxxx [mailto:oracle-l-bounce@xxxxxxxxxxxxx] On Behalf Of Dennis Williams Sent: Monday, December 29, 2008 12:39 PM To: Oracle List Subject: Oracle 8i and 9i on same Windows server? List, We are upgrading a database server to Oracle 10g (10.2.0.4) over the holiday. It was just discovered that one Windows report server is using an Oracle 8i client (Windows 2000 I think). Has anyone had any problems with this configuration? As a contingency, we are considering installing the 9i client, but want to keep the 8i client available as a contingency. Does anyone recall any problems installing the 9i client without disturbing the existing 8i client? Thanks, Dennis Williams