Sixteen patients with moderately severe essential hypertension completed a double-blind crossover trial with four treatment periods each lasting for six weeks. They received in random order, placebo; tienilic acid 250 mg/day; propranolol 80 mg b.d.; and tienilic acid 250 mg/day and propranolol 80 mg b.d. in combination. Mean blood pressure in the lying position was 169/98 mmHg on placebo, 157/94 mmHg on tienilic acid, 159/90 mmHg on propranolol and 142/86 mmHg on the combination of tienilic acid and propranolol. The effects of tienilic acid and propranolol on blood pressure were additive and there was no evidence of any interaction. The onset of the hypotensive effect of tienilic acid was gradual while the effect of propranolol was maximal within 2 weeks of the start of treatment. Tienilic acid produced a significant reduction in serum urate from 0.33 mmol/l to 0.18 mmol/l. The combination of tienilic acid and propranolol in the doses used in the trial was effective and acceptable in the reduction of raised blood pressure.