A slow-release tablet containing 12.5 mEq of potassium chloride was compared with a potassium chloride solution in normal human subjects under controlled conditions. Changes in plasma potassium concentration and rates of urinary potassium excretion indicate the tablet is absorbed in a slow, sustained fashion in contrast to the solution. Net potassium excretion after single and multiple doses indicates that the amount of potassium absorbed from the slow-release tablet is comparable to the solution. The slow-release potassium chloride tablets were well tolerated and were effective in correcting experimentally induced potassium depletion of moderate severity. Gastrointestinal tract irritation was not apparent and fecal 51Cr red blood cell loss after the tablet and the solution were of the same order.