 <p>RTRIM removes characters specified in the second parameter from the end of the string specified in the first. Since the last character of 'VTR 564-31 / V16 H12 W08 E19 L14' is a '4', which is not specified in the second parameter ' /', there is nothing to trim.</p> <p>It looks like you think it looks for the first occurence of ' /' in the first string and removes everything from there on, but that's not what it does.</p> <p>For example:</p> <pre><code>SQL&gt; select rtrim('AAABBBCCCBBBAAA','AB') from dual; RTRIM('AA --------- AAABBBCCC </code></pre> <p>RTRIM removed all the As and Bs from the <strong>end</strong> of the string.</p> <p>Probably what you actually want is:</p> <pre><code>select substr(yourstring, 1, instr(yourstring, ' / ')-1) from dual; </code></pre> <p>i.e. use INSTR to locate the position of ' / ' and then SUBSTR to get just the part of "yourstring" before that.</p>