The NBA usually invites players expected to be drafted among the top-15 selections.
Leonard, 7-foot-1, 250 pounds, entered this year's draft following his sophomore season at Illinois. He averaged 13.6 points, 8.2 rebounds and 1.9 blocks last season.
ESPN NBA draft analyst Chad Ford has projected Leonard to be selected No. 9 overall by the Detroit Pistons in his latest mock draft.
The NBA draft will be televised on ESPN and ESPN3.com beginning at 6 p.m. on Thursday.