While contact in girls' lacrosse is prohibited, concussions can and do occur. 

The two most recent studies of concussion rates among high school athletes (1,2) report concussion rates in girl's lacrosse essentially tied with girl's soccer for the highest among girl's sports, nearly as high as the concussion rate in boy's lacrosse (not statistically different in terms of rates), and almost double the rate of the girl's sport with the next highest concussion rate (basketball).