  We have shown that higher dimensional Reissner-Nordstr\"om-de Sitter black
holes are gravitationally unstable for large values of the electric charge and
cosmological constant in $D \geq 7$ space-time dimensions. We have found the
shape of the slightly perturbed black hole at the threshold point of
instability. Why only $D=4, 5$ and 6 dimensional worlds are favorable as to the
black stability remains unknown.
