A controlled clinical trial carried out on 538 patients admitted to an acute geriatric hospital confirms a previous finding that low vitamin C levels in the female are associated with an increased mortality at four weeks following admission. This mortality is not significantly influenced by the administration of 200 mg daily of ascorbic acid. A variable response in L.A.A. levels was noted in the group receiving active tablets. Those who responded with a rise in vitamin C levels had a significantly lower four-week mortality than those who showed no response. Those assessed as moderately or severely ill had a lower vitamin C level on admission and a higher mortality four weeks following admission than the group assessed as not significantly ill. The possible explanations for these findings are discussed and the view expressed that stress factors are important in determining L.A.A. vitamin C levels, and that figures based on these and plasma levels are not a reliable indication of vitamin C status and are of doubtful value in the diagnosis of deficiency states.