  We investigate the relic abundance of dark matter from coannihilation in
non-standard cosmological scenarios. We explore the effect of coannihilation on
the relic density of dark matter and freeze out temperature in quintessence
model with kination phase and brane world cosmological scenarios. Since the
Hubble expansion rate is enhanced in quintessence and brane world cosmological
models, it causes the larger relic density compared to that in the standard
one. On the other hand, the relic density of dark matter is decreased due to
the coannihilation in the standard cosmological scenario. After including
coannihilation in quintessence or brane world cosmological scenarios, we find
the decrease of the relic density of dark matter is slightly slower than that
in the standard cosmological scenario.
