In a double-blind trial, 194 ambulatory elderly patients (mean age, 74 +/- 8 years) recovering from acute illnesses were randomly assigned to receive either ornithine oxoglutarate (OGO) or a placebo. Nine subjects withdrew during the study, six in the OGO group and three in the placebo group. OGO and the placebo were administered once daily at a dose of 10 g after lunch for 2 months; the patients were monitored for a total of 4 months. Efficacy was evaluated in terms of nutritional variables, quality of life and total cost of medical treatment. The analysis involved a total of 185 patients (93 in the placebo group and 92 in the OGO group). The two groups were comparable at inclusion. After 30 and 60 days of treatment, there was a significant improvement in the following variables in the OGO group relative to the placebo group: appetite (p < 0.001), body weight (p < 0.001) and independence (p < 0.01). Two months after the end of treatment, there was still a significant improvement in the quality-of-life index (p < 0.001) and the medical-cost index (p < 0.03) in the OGO group, with an overall cost saving of 37%. We conclude that OGO seems to be a cost-effective nutritional supplement for elderly convalescent patients.