Dropping a tlistview onto a form and checking the property \'AlternatingColors\' to true, by default it will show a grey background on every other item on the listview.
You need to edit the style of TlistView.
Right-click on listview, choose "Edit Custom Style" and in the structure panel there are two items: "itembackground" and "alternatinfitembackground".
You can change the colors from there.