Unknown to its hypertension specialists, a major teaching hospital changed the cuffs on its sphygmomanometers from manufacturer-validated to a uniform washable alternative, in line with ‘Health and Safety’ concerns surrounding potential cross-contamination between patients. When clinic doctors suspected serious under-reading with the new cuffs, a systematic comparison was undertaken in 54 patients using two UM-101 sphygmomanometers: one using the original, manufacturer-supplied cuff and the other with the washable replacement. The study confirmed an average under-reading of 8±10/5±5 mm Hg using the washable cuff, and a third of patients with poorly controlled hypertension were considered normotensive, after using this cuff. The UM-101 sphygmomanometers have now been re-fitted with the original cuffs. Sphygmomanometer cuffs are not interchangeable between devices and a modicum of common sense should be shown to prevent changes made in the name of Health and Safety from having the opposite effect to that intended.