  The branching ratios of K^- absorption at rest in nuclear matter are
evaluated from the K^- self-energy by using the chiral unitary approach for the
s-wave \bar{K} N amplitude. We find that both the mesonic and non-mesonic
absorption potentials are dominated by the \Lambda(1405) contributions. We also
observe that the mesonic absorption ratio [\pi ^{-} \Sigma ^{+}] / [\pi ^{+}
\Sigma ^{-}] increases as a function of nuclear density due to the interference
between \Lambda(1405) and the I=1 non-resonant background, which is consistent
with experimental results. The fraction of the non-mesonic absorption is
evaluated to be about 30 % at the saturation density. The branching ratios of
the K^- absorption at rest into deuteron and 4He are also calculated.
