How can i determine the number of children, which nodename starts with a certain string, e.g. "level"?

Use the starts-with function, e.g. this gives you all children of the context node that start with "level":
this gives you all descendants of the context node that start with "level":
If you are using namespaces then replace name() with local-name().



--

Joe (Microsoft MVP - XML)

I am guessing that by saying "nodename starts with", your xml may look like this:

  <levels>
    <level1></level1>
    <level2></level2>
    <level3></level3>
    <leveln></leveln>
  </levels>

If context is "levels" :

  <xsl:value-of select="count(*[starts-with(name(), 'level')])" />

If namespaces are involved you might want to use the local-name() function instead.

Regards
Bryan