Characters.Insert Method (Excel) limits text to 255 characters
<p>It is really impossible to append more than 255 chars into a single cell by VBA macro in MS Excel?</p>

<p>Sample code:</p>

<pre><code>Option Explicit
Sub TestSub()
  Dim L As Long
'  Const str = "1" &amp; vbLf
  Dim i As Integer
  Range("A1").ClearContents
  Range("A1").WrapText = True
  For i = 1 To 260  ' any number greatest than 255
    L = Range("A1").Characters.Count
    Debug.Print L
    Range("A1").Characters(L + 1, 1).Insert ("A")
  Next i
End Sub
</code></pre>

<p><em>Added:</em>
It is important to save previous formatting of chars in cell.</p>