Senator Martin McAleese has today submitted his letter of resignation to the Seanad.
The Oireachtas has confirmed the Cathaoirleach has received the letter.
He first joined the Seanad back in May 2011. Shortly after his appointment, he was asked to chair the committee investigating the Magdalene laundries.
The report has been completed after 18 months, and is to be published shortly.
He has also paid tribute to Taoiseach Enda Kenny, thanking him for his appointment.
Senator McAleese's wife, former President Mary McAleese, left office in 2011.