We study the possibility of non-singular black hole solutions in the theory
of general relativity coupled to a nonlinear scalar:field with a positive
potential possessing two minima: a 'false vacuum' with;positive energy and
a 'true vacuum' with zero energy. Assuming that the scalar field starts 'at
the false vacuum at the origin and comes to the true vacuum at spatial inf
inity, we prove a no-go theorem by extending a no-hair theorem to the black
hole interior: no smooth solutions exist which interpolate between the loc
al de Sitter solution near the origin and the asymptotic Schwarzschild solu
tion through a regular event horizon or several horizons.