Thanks !
It works but the option values are needed in the eCart to calculate the price, which depends on the choosen size. So I can't change them like in your model.
<select name="FrogStyling_1_Size_Add" id="FrogStyling_1_Size_Add" class="textfieldReg" onchange="document.getElementById('cmPrice').innerHTML = document.FrogStyling_1_ATC_<%=rsDetail.Fields("ProductID").value%>.FrogStyling_1_Size_Add[document.FrogStyling_1_ATC_<%=rsDetail.Fields("ProductID").value%>.FrogStyling_1_Size_Add.selectedIndex].value" >
<option value="10">10 cm - € 1,00</option>
<option value="15" selected="selected">15 cm</option>
<option value="20">20 cm + € 2,00</option>
<option value="25">25 cm + € 4,00</option>
<option value="30">30 cm + € 5,00</option>
<option value="35">35 cm + € 6,00</option>
<option value="40">40 cm + € 7,00</option>
<option value="45">45 cm + € 8,00</option>
<option value="50">50 cm + € 9,00</option>
<option value="55">55 cm + € 10,00</option>
</select>
Isn't it possible to change the .value of the onchange event with a conditional statement ?