  The probability of Z-boson decay to a pair of charged fermions in a strong
electromagnetic field, is calculated. On the basis of a method that employs
exact solutions to relativistic wave equations for charged particles, analytic
expressions for the partial decay widths of Z-boson are obtained at an
arbitrary value the external-field strength. The total Z-boson decay width in
an intense electromagnetic field, is calculated by summing these results over
all known generations of charged leptons and quarks. It is found that, in the
region of relatively weak fields, the field-induced corrections to the standard
Z-boson decay width in a vacuum do not exceed 2%. As the external-field
strength increases, the total decay width develops oscillations against the
background of its gradual decrease to the absolute-minimum point. In the region
of strong fields the total decay width of Z-boson grows monotonically. In this
case the t-quark-production process, which is forbidden in the absence of an
external field, begins contributing significantly to the total decay width of
the Z-boson.
