Prime Minister Tony Abbott is ''a sexist'' and the Coalition has been ''dog whistling'' with its asylum seeker policies, says retiring Liberal senator Sue Boyce in an extraordinary exit interview.

Reflecting on her career in Parliament - she retires at the end of June - Senator Boyce said she thought Julia Gillard's famous misogyny speech was ''powerful'' and, for Ms Gillard's purposes, ''a brilliant speech''. But she thought the former prime minister had used the wrong word to describe Mr Abbott.

Senator Sue Boyce gives her valedictory speech. Credit:Andrew Meares

''I think it would have been more accurate if she had called him a sexist,'' she said.

''But singling [Mr Abbott] out as a sexist was not reasonable either,'' she added, saying the Prime Minister was one of many ''subtle'' sexists in federal Parliament.