Originally Posted by mamartinezp
Do someone know what is the best version for RHEL 5 for install Oracle Enterprise 11g?
Yes...Red Hat and/or Oracle sales would know this. Both of these are commercial, PAY FOR products, and are NOT free.
Also, since the latest version of RHEL is 6.x, installing 5 wouldn't be recommended. Install the latest version of RHEL, and the Oracle installation notes will tell you what you need to modify to get it working. Starting out with an old version of the server OS (even if it IS still supported), is a bad idea.