  In a diquark-diquark-antiquark picture of the pentaquark we study the decay
$\Theta \to K^{+} n$ within the framework of QCD sum rules. After evaluation of
the relevant three-point function, we extract the coupling $g_{\Theta nK}$
which is directly related to the pentaquark width. Restricting the decay
diagrams to those with color exchange between the meson-like and baryon-like
clusters reduces the coupling constant by a factor of four. Whereas a small
decay width might be possible for a positive parity pentaquark, it seems
difficult to explain the measured width for a pentaquark with negative parity.
