1. Direct intra-arterial blood pressure (radial artery) has been compared with indirect blood pressures using a regular sized adult cuff and a thigh cuff, with a mercury sphygmomanometer, in 24 hypertensive patients aged 62--84 years, and in 16 hypertensive patients aged 29--59 years. 2. The patients were studied because they were suspected of having a false elevation of their indirect blood pressure, since they had diastolic pressures over 100 mmHg, without hypertensive retinopathy, cardiac hypertrophy, or nephropathy. 3. Indirect diastolic pressure was falsely elevated by 30 mmHg or more in 12 out of 24 of the subjects over age 60, and in four of the 16 of those under age 60. Pseudohypertension (indirect diastolic greater than 100 mmHg, direct diastolic greater than 90 mmHg) was present in 12 subjects over age 60 and 5 under age 60. 4. Errors in indirect measurement of blood pressure are a serious problem, particularly in the elderly. Direct intra-arterial measurement may be useful in the management of hypertension.