Seventy-five patients, 55 years or older, were treated for major depression with either nortriptyline, phenelzine, or placebo during a 7-week period. There was a significantly greater mean orthostatic fall in systolic pressure in patients treated with nortriptyline and phenelzine as compared to the placebo group, but no significant difference was evident between the nortriptyline and phenelzine groups. The orthostatic changes appeared during the first week of treatment and were not correlated with plasma level of nortriptyline, percent platelet monoamine oxidase inhibition, or pretreatment orthostatic changes.