The pharmacokinetics of amitryptyline (AMI), a tricyclic antidepressant, were evaluated in 6 healthy elderly human volunteers (72-83 yr of age) after a single oral dose of 125 mg of AMI-HCl. AMI was absorbed rather slowly (mean peak time 10.4 .+-. 1.6 h), but very efficiently. The rate of formation of nortriptyline (NT) and the apparent clearance values (0.18-0.45 1/h/kg) of AMI were significantly lower than those previously described for younger subjects. Reversible alterating ECG were observed in 5 cases concomitantly with AMI peak plasma concentrations. The results indicate the desirability of reduced and divided daily doses of AMI in the elderly.