This paper reviews the literature on a century-old controversy relating to the error that may be introduced to blood pressure (BP) measurement by using a cuff with a bladder of inappropriate dimensions for the arm for which it is intended. The use of cuffs containing inappropriate bladders is a serious source of error which must inevitably lead to incorrect diagnosis in practice, and erroneous conclusions in hypertension research. There is unequivocal evidence that either too narrow or too short a bladder (undercuffing) will cause overestimation of BP and there is growing evidence that too wide or too long a bladder (overcuffing) may cause underestimation of BP. Undercuffing has the effect in clinical practice of overdiagnosing hypertension and overcuffing leads to hypertensive subjects being diagnosed as normotensive. Either eventuality has serious implications for the epidemiology of hypertension and clinical practice. A detailed review of the literature permits a definitive statement on bladder dimensions for a given arm circumference and clearly indicates that substantial error is caused by the use of inappropriate cuffs. On the basis of this review and aware of the advances in cuff design, the features for an 'Adult Cuff', which would be applicable to all adult arms, are proposed in this paper, and it is hoped that manufacturers may take up the challenge of producing such a cuff.