I am supposing you're trying to update a field in a table. If that is wrong,
I'm sorry for the following, as it will not apply to you.

Use the following code to update a memo field in a table by appending a text
string to the end of it. (Add a WHERE clause to ensure you change only the
record you want):

CurrentDb.Execute "UPDATE tblMemo SET tblMemo.fldMemo = fldMemo & '" & [add
your string here] & "'"

  rs("MemoField")=nz(rs("MemoField")) & "xxxxxx"
  rs.Update

or
dim strTemp as string

  strTemp=nz(rs("MemoField"))
  strTemp=strTemp & "xxxxxx"
  rs("MemoField")=strTemp
  rs.Update

One of these should be a help to you.

- Raoul