From what i hear they don't tolerate any strangers, unless raised with them. But how extreme are these guys, when someone comes knocking at your door, or a stranger walks in your house and your dog is the only one home, pizza guy walks in... All that stuff, i also heard someone on this forum say their fila tries to break through the window to get at people outside. Are these dog's more of " keep the person away from the property", or " you will not leave alive, to the pizza guy"? I'm not getting a fila btw, well not as my first mastiff breed that's for sure.