Thanks very much for the reply. I've tried your suggested code and it does seem to loop though now, so that's great. However, it doesn't write out the value for categoryName. My code now is: 

XmlTextReader xtr = new XmlTextReader("http://url.feed.com"); 
    xtr.WhitespaceHandling = WhitespaceHandling.None;


    XmlDocument X = new XmlDocument();
    X.Load(xtr);


    if (!(X == null))
    {
        try
        {
            XmlNodeList ArticleList = X.SelectNodes("InfoStreamResults/Article");
            foreach(XmlNode Article in ArticleList)
            {
                

                try
                {
                    XmlNodeList CatNodesList = Article.SelectNodes("Categories/Category");
                    foreach( XmlNode category in CatNodesList)
                    {
                      

                        if (Article.SelectSingleNode("Category") != null)
                        {
                            categoryName = EncodeIt(Article.SelectSingleNode("Category").Value);
                            Response.Write(categoryName);
                            Response.Write("<br />");
                        }


                    }


                }
                catch (Exception ex)
                {
                    Response.Write(ex);
                    Response.Write("<br />");


                }
  



            }
        }
        catch (Exception ex)
        {
            Response.Write(ex);
        }
    }

In the above, we don't enter the if statement on line 22. Is this the right way of referencing the node? I would have thought that now we are in another foreach loop, it would become  category.SelectSingleNode("category"). But I tried that and that didn't work either.

 Incidentally, a sample of my XML looks like this;

 
<InfoStreamResults Copyright="(c) 2006 xxxx." ArticleCount="1">
<Article Created="12:05:00" ID="1111">
  <Heading>heading title</Heading> 
  <Date>11/11/1111</Date> 
<Contents>
![CDATA[ blah blah ]]> 
  </Contents>

<Categories>
  <Category ID="11111">cat 1</Category>
<Category ID="11112">cat 2</Category>
  </Categories>
  </Article>

</InfoStreamResults>

You can see the Categories node as above and the two values inside it. How do you loop through each article, then loop through each set of Categories inside each Article, and get the value of each Category? Getting there - any more pointers much appreciated.