Assuming you have a DIV element having id = “div1″ funtcion ShowDIV() {  jDiv.fadeIn(500); var jDiv = $(“#div1″); var div = jDiv.get()[0]; var top = Math.round((document.documentElement.clientHeight / 2) – (div.clientHeight / 2) + document.documentElement.scrollTop) + ‘px’; var left = Math.round((document.documentElement.clientWidth / 2) – (div.clientWidth / 2)) + ‘px’; div.style.top = top; div.style.left = left; } [...]

Continue reading about How to show a DIV element on the screen-center using JQuery