Make sure you set a Font that supports the characters you’re trying to display. OK, so what are you supposed to do? Set the Font! 9 times out of 10, this preference fixes the problem with display issues. This can lead to corrupt data if conversions are necessary. When these settings are the same, Oracle Database assumes that the data being sent or received is encoded in the same character set as the database character set, so character set validation or conversion may not be performed. Setting NLS_LANG correctly enables proper conversion from the client operating system character encoding to the database character set. The character set that is specified by the NLS_LANG parameter should reflect the setting for the client operating system. Setting the NLS_LANG parameter properly is essential to proper data conversion. Having the wrong NLS parameters locally can be bad. The these parameters work together with the database so that information can be transferred back and forth correctly. These should accurately reflect the language and locality setup on your LOCAL machine. Well, it starts with a basic misunderstanding of NLS Client parameters. This question appears on the forums about every week or so as well. When I use the old and deprecated SQL*Plus (windows rich client) I can see the hebrew clearly, when I use the latest SQL Developer, I get gibberish. I’m from Israel, and the language on the databases is Hebrew. I get a variation on this question at least once a week, if not more frequently.