Diffuse brain injuries are very common in side impacts, accounting for more than half of the injuries to the head. These injuries are often sustained in less severe side impacts. An English investigation has shown that diffuse brain injuries often originate from interior contacts, most frequently with the side window. They are believed to be mainly caused by quick head rotational motions.This paper describes a test method using a Hybrid III dummy head in a wire pendulum. The head impacts a simulated side window or an inflatable device, called the Inflatable Curtain (IC), in front of the window, at different speeds, and at different impact angles. The inflated IC has a thickness of around 70 mm and an internal (over) pressure of 1.5 bar. The head was instrumented with a three axis accelerometer as well as an angular velocity sensor measuring about the vertical (z) axis. The angular acceleration was calculated. The head impact speeds ranged up to 7 m/s, a speed at which the Inflatable Curtain barely bottoms out. The recorded data for linear acceleration, angular acceleration and angular velocity were compared with corresponding threshold values found in the literature.It was concluded that the Inflatable Curtain has the potential to substantially decrease the risk of sustaining diffuse brain injuries. The IC reduced the maximum linear acceleration and HIC up to 70% and the peak angular acceleration up to 70%, depending on the contact angle between the head and the IC. The peak angular velocity was reduced up to 30%.