Which grand slams has lleyton hewitt won?

US Open and Wimbledon.

Lleyton Hewitt has won 2 Grand Slam Titles in Singles and 1 in Doubles. In singles, Hewitt won the US Open in 2001 against Pete Sampras and Wimbledon in 2002 against David Nalbandian. In doubles, he won the US Open in 2000 with his partner Max Mirnyi.

He has been runner-up twice in singles (2014 US Open and 2005 Australian Open) and once in mixed doubles (2000 Wimbledon with Kim Clijsters).