Mary Robinson (born 21 May 1944 ) was the first female President of Ireland , serving from 1990 to 1997. She defeated Fianna Fail 's Brian Lenihan in the 1990 presidential election , becoming the first non-Fianna Fail president in the office's history and the first Labour president. She resigned the presidency four months ahead of the end of her term of office to take up the post of the United Nations High Commissioner for Human Rights . factbook.org