The body of a woman in her 40s was found in an apartment on Castlebar Street in Westport on Saturday 31st of July.
Gardai launched an investigation and today two men, in their 30s and 50s, are being detained at Castlebar Garda Station.
They can be held for up to 24 hours.
Officers say a post-mortem exam has been completed, but the results are not being released for operational reasons.