Season Episodes Originally aired First aired Last aired 9 March 27, 2005 (2005 - 03 - 27) May 22, 2005 (2005 - 05 - 22) 27 September 25, 2005 (2005 - 09 - 25) May 15, 2006 (2006 - 05 - 15) 25 September 21, 2006 (2006 - 09 - 21) May 17, 2007 (2007 - 05 - 17) 17 September 27, 2007 (2007 - 09 - 27) May 22, 2008 (2008 - 05 - 22) 5 24 September 25, 2008 (2008 - 09 - 25) May 14, 2009 (2009 - 05 - 14) 6 24 September 24, 2009 (2009 - 09 - 24) May 20, 2010 (2010 - 05 - 20) 7 22 September 23, 2010 (2010 - 09 - 23) May 19, 2011 (2011 - 05 - 19) 8 24 September 22, 2011 (2011 - 09 - 22) May 17, 2012 (2012 - 05 - 17) 9 24 September 27, 2012 (2012 - 09 - 27) May 16, 2013 (2013 - 05 - 16) 10 24 September 26, 2013 (2013 - 09 - 26) May 15, 2014 (2014 - 05 - 15) 11 25 September 25, 2014 (2014 - 09 - 25) May 14, 2015 (2015 - 05 - 14) 12 24 September 24, 2015 (2015 - 09 - 24) May 19, 2016 (2016 - 05 - 19) 13 24 September 22, 2016 (2016 - 09 - 22) May 18, 2017 (2017 - 05 - 18) 14 24 September 28, 2017 (2017 - 09 - 28) May 17, 2018 (2018 - 05 - 17)
when did season 4 of greys anatomy come out
September 27, 2007