  We consider a self-consistent system of spinor and scalar fields within the
framework of a Bianchi type I gravitational field filled with viscous fluid in
presence of a $\Lambda$ term. Exact self-consistent solutions to the
corresponding spinor, scalar and BI gravitational field equations are obtained
in terms of $\tau$, where $\tau$ is the volume scale of BI universe. System of
equations for $\tau$ and $\ve$, where $\ve$ is the energy of the viscous fluid,
is deduced. Some special cases allowing exact solutions are thoroughly studied.
