E ai, beleza. Peguei esse codigo na net, acho que é o que você procura. <!-- --><form name="doublecombo"> <p><select name="example" size="1" onChange="redirect(this.options.selectedIndex)"> <option>Technology Sites</option> <option>News Sites</option> <option>Search Engines</option> </select> <select name="stage2" size="1"> <option value="http://wsabstract.com">Website'>http://wsabstract.com">Website Abstraction</option> <option value="http://www.news.com">News.com</option>'>http://www.news.com">News.com</option> <option value="http://www.wired.com">Wired'>http://www.wired.com">Wired News</option> </select> <input type="button" name="test" value="Go!" onClick="go()"> </p> <script> <!-- /* Double Combo Script Credit By Website Abstraction (www.wsabstract.com) Over 200+ free JavaScripts here! */ var groups=document.doublecombo.example.options.length var group=new Array(groups) for (i=0; i<groups; i++) group=new Array() group[0][0]=new Option("Website Abstraction","http://wsabstract.com") group[0][1]=new Option("News.com","http://www.news.com") group[0][2]=new Option("Wired News","http://www.wired.com") group[1][0]=new Option("CNN","http://www.cnn.com") group[1][1]=new Option("ABC News","http://www.abcnews.com") group[2][0]=new Option("Hotbot","http://www.hotbot.com") group[2][1]=new Option("Infoseek","http://www.infoseek.com") group[2][2]=new Option("Excite","http://www.excite.com") group[2][3]=new Option("Lycos","http://www.lycos.com") var temp=document.doublecombo.stage2 function redirect(x){ for (m=temp.options.length-1;m>0;m--) temp.options[m]=null for (i=0;i<group[x].length;i++){ temp.options=new Option(group[x].text,group[x].value) } temp.options[0].selected=true } function go(){ location=temp.options[temp.selectedIndex].value } //--> </script> </form><!-- --> Até mais....