You should use the form_multiselect() helper.

$options = array(                  'small'  => 'Small Shirt',                  'med'    => 'Medium Shirt',                  'large'   => 'Large Shirt',                  'xlarge' => 'Extra Large Shirt',                );echo form_multiselect('shirts', $options);

The only thing that comes to my mind is using an array with more than one empty element:

$options = array(                  'small'  => 'Small Shirt',                  'med'    => 'Medium Shirt',                  'large'   => 'Large Shirt',                  'xlarge' => 'Extra Large Shirt',                );$array = array('','');echo form_dropdown('shirts',$options, $array);

This code works, though not the most elegant out there.

UPDATE:

This is even better, didn't remember it at first!

echo form_multiselect('shirts',$options,'','');

Output:

<select name="shirts" multiple="multiple"><option value="small">Small Shirt</option><option value="med">Medium Shirt</option><option value="large">Large Shirt</option><option value="xlarge">Extra Large Shirt</option></select>

i tried every solution but no one works with me i tried ( form_dropdown from from helper) i also tried ordinary way with multiple= "multiple"

is it common problem with codeigniter ??

Updatethe error was that anyone forget to name in html attribute as array cars[]

<select **name="cars[]"** multiple="multiple">  <option value="volvo">Volvo</option>  <option value="saab">Saab</option>  <option value="opel">Opel</option>  <option value="audi">Audi</option></select>

this works fine always .