The serum levels of tiaprofenic acid were determined by HPLC in 20 geriatric patients with ischemic heart disease, and the pharmacokinetic parameters were calculated. The results indicate that in geriatric patients the drug does not accumulate when given at a dose of 300 mg twice a day. Sufficient plasma levels are reached and the short terminal phase half-life prevents accumulation. The electrolyte balance was examined during the 7 days of treatment, and no change in sodium and potassium levels in the serum or in urine were observed. Weight as well as blood pressure of the patients remained constant, so that an increased development of edema, especially with regard to the existing ischemic heart disease of the patients, could be excluded. The results of our study indicate that tiaprofenic acid at the employed dosage is suitable for the therapy of arthritis in geriatric patients suffering from ischemic heart disease, without accumulation of the drug or the development of edema.