1. A new piece of equipment, the quantitative colour television image analyser, has been introduced as providing a superior method for measuring bone density.

2. This method produces not only a numerical result but also a pattern of density distribution in the form of a seven colour contour map.

3. The changes in twenty rheumatoid hands at an interval of one year have been measured. The metacarpals and proximal phalanges always lose bone, but the metacarpo-phalangeal joint may gain in density if the disease process is far advanced. Some areas can lose 50 per cent of bone in one year.