Mary Hart To Leave 'Entertainment Tonight'.

After almost three decades of imbuing ''Entertainment Tonight'' with one of the perkiest dispositions and some of the shiniest teeth on television, Mary Hart said on Thursday that she would leave that syndicated pop-culture show at the end of its coming 30th season. Ms. Hart, right, a Miss South Dakota turned television broadcaster, joined the fast-paced ''Entertainment Tonight'' in 1982. In a statement she said: ''I've reached a point when I clearly realize it's time for a change. There are many things I want to do in my life, and I'd better get on with them. It will certainly be with mixed sentiments that I say goodbye at the end of the season, but it will definitely be with a sense of celebration.'' The coming season of ''Entertainment Tonight'' is to have its premiere on Sept. 13. CBS Television Distribution, which produces the series, said no decision had been made on Ms. Hart's replacement. [ABSTRACT FROM PUBLISHER]