The efficacy and tolerability of a once-daily, fixed combination of 50 mg atenolol and 20 mg nifedipine slow release were evaluated in a 12-month open study of 27 elderly hypertensives who were either newly presenting patients or were those who were inadequately controlled on previous monotherapy or had unacceptable side-effects with their current therapy. After 1-month's therapy with the combination, the mean sitting blood pressure 1 to 4 hours post-dose decreased from 176/103 mmHg to 146/83 mmHg and was maintained at this level for the remainder of the study. Eight patients complained of side-effects on study entry. Sixteen had complaints at some time during the 12 months of fixed combination treatment and 4 were withdrawn because of side-effects. Dizziness occurred in 6 patients on the combination but, as with side-effects overall, tended to resolve with time; its occurrence did not appear to correlate with the on-treatment blood pressure. In this group of elderly hypertension patients, therefore, the combination therapy with atenolol plus nifedipine slow release appeared to exert a greater antihypertensive effect compared with previous therapy, which included atenolol alone, with no evidence of tachyphylaxis and was reasonably well-tolerated over a 12-month period.