  The effects of non-magnetic disorder on the critical temperature T_c of
organic weak-linked layered superconductors with singlet in-plane pairing are
considered. A randomness in the interlayer Josephson coupling is shown to
destroy phase coherence between the layers and T_c suppresses smoothly in a
large extent of the disorder strength. Nevertheless the disorder of arbitrarily
high strength can not destroy completely the superconducting phase. The
obtained quasi-linear decrease of the critical temperature with increasing
disorder strength is in good agreement with experimental measurements.
