The alarm was raised at around 6 o'clock yesterday evening by a caller who discovered the man's body at a house on McDonagh Street.
It's understood the 36 year old was found in the shower of the bathroom and while Gardai haven't released any details of injury, it's reported there was blood at the scene
An ambulance was dispatched but a local doctor pronounced him dead at the scene.
The area was sealed off pending a full technical examination and the office of the State Pathologist notified
A preliminary examination is due to take place this morning before the body is removed to University Hospital Limerick for a full post-mortem
Nenagh Gardai are investigating all aspects into the man's death but currently are treating it as suspicious