The results in this paper reveal
a dichotomy in regard to the existence of fixed points for smooth real maps and
biholomorphic maps in Hilbert space. Kakutani has shown that there exists a
homeomorphism of the closed unit sphere of Hilbert space onto itself which has no
fixed point. A slight modification of his example shows that there is a diffeomorphism
having the same property. Our results show that in the complex case every
biholomorphic map of the unit ball onto itself in Hilbert space has a fixed
point.