Lap belts, fitted to the centre seats of Australian cars for the past 22 years, have come under criticism as being injurious to children. The weight of evidence is that lap belts provide substantial protection, though less than three-point belts. A specific injury, the seat belt syndrome (SBS), to abdominal viscera and/or lumbar spine has been particularly associated with lap belts, an association confirmed by a hospital-based study in Melbourne. Roadside observations of belt use and Transport Accident Commission claims permitted the calculation of the incidence of SBS and the relative risks of SBS by seated position. The centre rear seat (lap belt) carried about twice the risk of SBS as outboard rear seats (three-point belts), which in turn have 2.7 times the risk of the outboard front seat. The number of SBS cases in Victoria has increased with penetration of the car fleet by 1971 and later cars. Suggestions are made for improvements in the restraint system.