This study investigated the effects of continuous therapy with oxygen on the neuropsychologic functioning of aged subjects professing problems with their memory. Nineteen men (mean age, 71 years) were evaluated on eight neuropsychologic measures during three different periods of time. Subjects were tested before any treatment, after a month of continuous therapy with oxygen, and after a period of sham treatment. The results indicated statistically significant improvement in the Wechsler Memory Quotient and, with one exception, improvement in all other measurements in favor of the treatment with oxygen. Differences between the results of this investigation and those of other studies are discussed, along with the factors possibly accounting for these differences.