 Grey 's Anatomy 's first season commenced airing as a mid @-@ season replacement to Boston Legal on March 27 , 2005 and concluded on May 22 , 2005 . The nine @-@ episode season aired on Sundays in the 10 : 00pm EST time slot , following Desperate Housewives . The show was renewed by ABC for a second season , that aired in the same time slot as season one . Premiering on September 25 , 2005 and concluding on May 15 , 2006 , the season consisted of twenty @-@ seven episodes . The first five episodes of the second season were originally scheduled to air during the first , but the network decided to close the first season of Grey 's Anatomy on the same night as Desperate Housewives ' finale . During the second season , Grey 's Anatomy produced two specials recapping the events of recent episodes , narrated by Bailey , entitled " Straight to the Heart " and " Under Pressure " . The show was renewed for a third season , which was relocated to the coveted Thursday 9 : 00pm EST time slot — a slot that the series has held onto since then . Commencing on September 21 , 2006 and ending on May 17 , 2007 , season three consisted of twenty @-@ five episodes . Two more specials were produced during the show 's third season , entitled " Complications of the Heart " and " Every Moment Counts " , which were narrated by Bailey and Morgan , respectively . 
