codice:
<script language="JavaScript">
arr_1 = new Array();
								arr_1[0] = 'BG';
								arr_1[1] = 'BS';
								arr_1[2] = 'CH';
								arr_1[3] = 'CO';
								arr_1[4] = 'LC';
								arr_1[5] = 'MI';
								arr_1[6] = 'SO';
								arr_1[7] = 'VA';
								arr_2 = new Array();
								arr_2[0] = 'AL';
								arr_2[1] = 'CN';
								arr_2[2] = 'NO';
								arr_3 = new Array();
								arr_3[0] = 'GO';
								arr_3[1] = 'UD';
								arr_4 = new Array();
								arr_4[0] = 'VE';
								arr_5 = new Array();
								arr_5[0] = 'PS';
								arr_6 = new Array();
								arr_6[0] = 'RN';
								arr_7 = new Array();
								arr_7[0] = 'SV';
								arr_8 = new Array();
								arr_8[0] = 'RM';
								


// Function to handle dynamically altering the contents of the City List box
function handleChange(regione){  
	regione=String(regione)
	var provincia, NumEntries, i
    provincia = document.frmricerca.provincia
	if (regione!='all'){
		NumEntries = eval("arr_" + regione + ".length")
		arr_prov=eval("arr_" + regione)
	}
	
  // Delete all entries in the cities list box
	  for (i = provincia.length; i > 0; i--){
		provincia.options[i-1] = null
	  }
	  
	  // Add comment option to City List box
	  provincia.options[0] = new Option("--","")
	
	  // If state is selected add its cities to the City List box
	  if (regione != 'all'){
		for (i = 1; i <= NumEntries; i++){
		  //GiocatoreSelect.options[i] = new Option((arrInter[newDisplay])[i-1],(i))
		  provincia.options[i] = new Option(arr_prov[i-1],arr_prov[i-1])
		}
	  }
	  provincia.selectedIndex = 0

}
</script>
e i due campi li crei così
codice:
<select NAME="regione" onChange="handleChange(this[this.selectedIndex].value)" class="input">
										<option SELECTED="SELECTED" VALUE="all">Tutte</option>

										
												<option value="1">Lombardia</option>
										
												<option value="2">Piemonte</option>
										
												<option value="3">FriuliVeneziaGiulia</option>
										
												<option value="4">Veneto</option>
										
												<option value="5">LeMarche</option>
										
												<option value="6">EmiliaRomagna</option>

										
												<option value="7">Liguria</option>
										
												<option value="8">Lazio</option>
										
									</select>
<select NAME="provincia" class="input">
										<option SELECTED="SELECTED" VALUE="">Tutte</option>
										
									</select>
da adattare alle tue esigenze...