We present a complete analytical theory of conductance fluctuations in
quantum dots in the regime of chaotic dynamics. Using the supersymmet
ry method we calculate for the first time exactly the conductance dist
ribution function for a system of noninteracting electrons. Knowledge
of this quantity enables us to obtain information about statistical pr
operties of wave functions of a closed dot. The far tail of the distri
bution function describes fluctuations of resonance conductance in the
Coulomb blockade regime.