Hola
@padawan@. Bienvenido al foro.
Prueba esto:
Código PHP:
<html>
<head>
<script>
function mostrar(frm,num) {
if(num==0) {
frm.txt1.style.visibility='visible';
frm.txt2.style.visibility='hidden';
}
else {
frm.txt1.style.visibility='hidden';
frm.txt2.style.visibility='visible';
}
}
</script>
</head>
<body>
<form>
<input type="radio" name="rad" checked="checked" onclick="mostrar(this.form,0)" />
<input type="radio" name="rad" onclick="mostrar(this.form,1)" />
<input type="text" name="txt1" />
<input type="text" name="txt2" style="visibility:hidden" />
</form>
</body>
</html>
Saludos,
