A five-year-old who is hitting and biting her parents, but is well behaved elsewhere does need some kind of professional help starting with a basic visit to your pediatrician. Schedule some time to talk with the doctor without your child present. Hitting and biting is pretty normal for a two-year-old (and needs to dealt with quickly and firmly), but I'd say it's outside the norm for a five-year-old. Is there a new baby on the way? Is she about to start Kindergarten? My two children had bouts of aggressive behavior like this and I usually found they needed more sleep, more fresh air and exercise, and a whole lot less of the stressful household routine. We were bringing stress home from work without even realizing it. I finally set up a 45-minute "chil time" right after we all got home. No expectations, no chores, no TV, no big dialog -- just snacks and hanging out together on the patio. That helped.