This paper describes results of a series of tests conducted during 1989 to evaluate further the UK Draft Specification for Motorcycle Leg Protectors (UKDS). Proposed in 1987, the UKDS involves leg protector elements which have specific geometric and mechanical properties to be verified by laboratory measurements. The full scale leg protector crash tests described are the most comprehensive to date in terms of: the types of motorcycles and cars used; the leg protector designs and UKDS categories; the type of impact configurations considered; and the use of state-of-the-art test methodologies, including a new motorcycle impact dummy and performance indices. Test results showed that UKDS type leg protectors lead to: increased numbers of leg fractures per crash; leg fractures resulting from leg protector contact; a lower head trajectory; and increased head impact velocity and acceleration. The lower head trajectory was ascribed to the restraining action of the leg protector as the upper body moves forward, diagonally to the side, or laterally during impact. In addition, the leg protector itself was seen to cause direct injury to the legs, due to upper leg combined load failure. Expressed in terms of injury severity and costs, the test results showed that UKDS leg protectors lead to increased total Abbreviated Injury Scale (AIS) scores and increased injury costs, in the majority of cases tested. For these reasons it was concluded that this general concept of leg protection is injury producing and does not contribute to improved rider protection.