Polymyalgia rheumatica and giant cell arteritis are amongst the most satisfying conditions for clinicians to diagnose and treat because the unpleasant effects and serious consequences of these conditions can be almost entirely prevented by corticosteroid treatment; the fact that the side-effects of this treatment sometimes seem to be more serious than the complications of the disease is an indication of its effectiveness. Unfortunately, there is no objective way of determining the prognosis in the individual, and decisions concerning duration of treatment remain empirical.