A double-blind placebo trial of vitamin C has been undertaken in 94 elderly "long-term" inpatients known to have initially low levels of plasma and leukocyte vitamin C (mean values 0.17 mg/100 ml plasma; 10.1 microgram/10(8) leukocytes). At the end of 2 months treatment, plasma and leukocyte vitamin C had increased considerably in those receiving C supplements, and in this group there were slight but significant increases in the mean values for body weight (0.41 kg), plasma albumin (0.46 g/l), and prealbumin (25.4 mg/l) compared with those receiving placebo therapy where there were decreases of 0.60 kg, 0.53 g/l, and 7.0 mg/l, respectively. There was also some clinical improvement as indicated by reductions in purpura and petechial hemorrhages in those receiving vitamin C, but no changes in mood or mobility were observed.