[walik]

<ul id="elems">
<li class="on">Test 1</li>
<li class="off">Test 2</li>
<li class="on">Test 3</li>
<li class="off">Test 4</li>
<li class="on">Test 5</li>
</ul>
<input type="checkbox" onclick="change(this)" /> спрятать
<script>
function change(obj) {
    var elems = document.getElementById('elems').getElementsByTagName('li');
    for(i=0;i<elems.length;i++) {
      if (elems[i].className == 'off') {
         if (obj.checked)
            elems[i].style.display = 'none';
         else
            elems[i].style.display = 'list-item';
      }
   }
}
</script>