A randomized double-blind study lasting 2 months was performed with either 25 mg captopril twice a day or 50 mg atenolol once a day in 125 patients with established diastolic hypertension (diastolic blood pressure greater than 95 mmHg) identified during a population screening programme of subjects aged less than 65 years. Quality of life was assessed from self-completed questionnaires. A significant fall in diastolic blood pressure occurred with both captopril (106.7 +/- 7.0 to 98.6 +/- 8.6 mmHg) and atenolol (107.4 +/- 7.5 to 98.2 +/- 8.1 mmHg) but there was no difference between the two drugs in the size of the fall. A measure of the number of symptomatic complaints, the symptom complaint rate, decreased with both drugs, by 1.3% for captopril and 3.1% for atenolol, but the difference between the drugs was not significant [1.8%; 95% confidence interval (Cl) - 1.3%, 4.9%]. There was a significant increase in the reporting of cough and runny nose in those on captopril compared with atenolol. A health index increased by 1.1% with captopril in comparison with no change on atenolol (difference 1.1%; 95% Cl - 2.0%, 4.2%). Psychological well-being was measured using the Symptom Rating Test. The improvement in total score was 1.4% with captopril and 2.3% with atenolol. The difference of 0.9% was not statistically significant (95% Cl - 1.2%, 3.0%).(ABSTRACT TRUNCATED AT 250 WORDS)