[root@brick ~]# echo $PATH
/usr/local/rvm/gems/ruby-1.9.2-p0/bin:/usr/local/rvm/gems/ruby-1.9.2-p0@global/bin:/usr/local/rvm/rubies/ruby-1.9.2-p0/bin:/usr/local/bin:/usr/lib/oracle/10.2.0.3/client64/bin:/usr/java/latest/bin/:/usr/kerberos/sbin:/usr/kerberos/bin:/usr/local/sbin:/usr/bin:/sbin:/bin:/usr/sbin:/usr/local/bin:/root/bin
[root@brick ~]# rvm use system
Now using system ruby.
[root@brick ~]# echo $PATH
/usr/local/bin:/usr/lib/oracle/10.2.0.3/client64/bin:/usr/java/latest/bin/:/usr/kerberos/sbin:/usr/kerberos/bin:/usr/local/sbin:/usr/bin:/sbin:/bin:/usr/sbin:/root/bin:/usr/local/rvm/bin
[root@brick ~]#

[root@brick ~]# grep PATH= .bash_profile
PATH=/usr/lib/oracle/10.2.0.3/client64/bin:/usr/java/latest/bin/:/usr/kerberos/sbin:/usr/kerberos/bin:/usr/local/sbin:/usr/bin:/sbin:/bin:/usr/sbin:/usr/local/bin:/root/bin

Note the /usr/local/bin near the end.  When you do "rvm use system" it's _that_ one which gets deleted, and not the one that was prepended.