OBJECTIVE: To pilot data collection instruments and to make a preliminary estimate of the level of incorrect use of car seat belts and child restraints in Fife, Scotland. DESIGN: Cross sectional survey of cars containing adults and children at a number of public sites across Fife in 1995 to assess use of car occupant restraints. Trained road safety officers assessed whether seat restraints were appropriate for the age of the passengers and whether restraints were used correctly. These assessments were based on standards published by the Child Accident Prevention Trust. PARTICIPANTS: The survey gathered data from 596 occupants in 180 cars: 327 adults and 269 children. Ten per cent of drivers who were approached refused to participate. Car occupant restraint was assessed in 180 drivers, 151 front seat passengers, and 265 rear seat passengers. MAIN RESULTS: Three hundred and sixty one occupants wore seat belts, 68 were restrained by a seat belt and booster cushion, 63 in toddler seats, 25 in two way seats, and 18 in rear facing infant carriers. Ninety seven per cent of drivers, 95% of front seat passengers, and 77% of rear seat passengers were restrained. However, in 98 (52%) vehicles at least one passenger was restrained by a device that was used incorrectly. Seven per cent of adults and 28% of children were secured incorrectly. The commonest errors were loose seat belts and restraint devices not adequately secured to the seat. Rates of incorrect use were highest in child seat restraints, reaching 60% with two way seats and 44% with rear facing infant seats. CONCLUSIONS: The incorrect use of car occupant restraints is an under-recognised problem, both by health professionals, and the general public. Incorrect use has been shown to reduce the effectiveness of restraints, can itself result in injury, and is likely to be an important factor in child passenger injuries. The correct use of car seat restraints merits greater attention in strategies aiming to reduce road traffic casualties. Areas of intervention that could be considered include raising public awareness of this problem, improving information and instruction given to those who purchase child restraints, and encouraging increased collaboration between manufacturers of cars and child restraints, in considering safety issues.