Classification of ankylosing spondylitis and spondylarthropathies is now satisfactory, but assessment of ankylosing spondylitis and related disorders could be improved. Currently, we do not completely encompass the spectrum of relevant outcomes. Functional status and toxicity assessment are frequently lacking. Although a considerable amount of progress has been made over the past decade in the development of patient status measures, this has mainly been achieved in rheumatic diseases that are characterized by predominant involvement of peripheral joints. This achievement is less prominent in ankylosing spondylitis. It may be relatively easy to define activity of extra-articular manifestations such as uveitis, but it is more difficult to define activity, severity, progress and outcome of a disease like ankylosing spondylitis with predominant spinal involvement.