The loads on a Hybrid III test dummy representing a child aged about 10 years have been analysed, based on results of crash tests carried out on seven motorcars. During the tests, the dummies were sitting on high-back booster seats, backless booster seats (booster cushions), or directly on the rear car seats and they were fastened with the use of standard car seatbelts. The differences in the seatbelt impact on the child, depending on the child restraint system used, have been pointed out. The analysis was done with using the crash test results published on the Internet by the US National Highway Traffic Safety Administration (NHTSA) and covering the case where the test car moving with a speed of about 56 km/h frontally hit a rigid flat barrier. The relations between dummy’s head, neck, thorax, and pelvis loads and the force exerted on the seatbelt have been shown. Attention has been directed to the fact that a child transported without a booster seat has a tendency to slide under the seatbelt, which in consequence may cause injuries to child’s abdomen and neck. A question has been examined whether the thoracic deflection can be limited by partial transfer of the load exerted by the seatbelt from dummy’s ribs to its shoulder.