The interactions of the lumbar spine and hip are particularly important to physical therapy for two reasons. The first reason is the challenge of determining whether pain in the hip region is from the lumbar spine, the hip or both. The second is that movements of the hip affect the lumbar spine and thus contribute to movement impairments. Therefore examination of the hip is consistent with the properties of the kinetic chain and the kinesiologic interaction of the back and hip. This lecture will describe the movement system impairment (MSI) syndromes of the lumbar spine and hip joint. The discussion will include factors contributing to these syndromes particularly as they relate to the passive and active characteristics of muscle and to the structural variations of the hip joints. The clinical and laboratory evidence of back and hip interactions will be discussed. The presentation will help clarify how the pain pattern and the examination that includes correcting the offending movement can assist the therapist in determining the regional source of the pain.