A technique is described for assessing lumbar sagittal mobility, which distinguishes between the motion of the upper and lower lumbar regions. The method employs a draughtsman's flexible curve and requires the location of three specific spinall and marks. Validation procedures were performed which show that the method is capable of recording ‘regional’ sagittal mobility and correlates well with other methods. The intra- and inter-observer accuracy of the method was explored and the results show it to be reproducible to less than 9% for the same observer and 15% for different observers. The flexicurve technique is inexpensive and simple both to learn and to use.