A multicenter, randomized double-blind study of 6 months' duration was performed in 540 patients (average age 54 years, 57% male) with mild-to-moderate essential hypertension to determine the relative effects on quality of life of cilazapril, atenolol, and nifedipine retard. Quality of life was assessed by using both a self-administered and an interviewer-administered questionnaire; the assessment included a complaint score (symptoms checklist), Health Status Index, assessment of work satisfaction, Psychological General Well-being Index, Profile of Mood States subscales, and life satisfaction assessment. Psychomotor function was measured by the Reitan Trail Making test B. At the end of the trial, diastolic blood pressure had fallen by an average of 15 mm Hg in all three groups, but significantly (p = 0.01) more patients taking cilazapril required the addition of a diuretic (36%) compared with those taking atenolol (25%) or nifedipine retard (24%). No significant differences in quality of life were observed between cilazapril and atenolol during the trial. Symptomatic complaints increased on nifedipine retard (p = 0.02) and contributed to a higher discontinuation rate (21% discontinued treatment compared with 13% and 14% taking atenolol and cilazapril, respectively, p = 0.04). However, a possible improvement in the fatigue subscale (p = 0.04) was also observed on nifedipine retard. The 95% confidence intervals showed that none of the drugs in this trial produced an effect equivalent to that previously reported between captopril and methyldopa in the Psychological General Well Being Index or between captopril and methyldopa or propranolol in Trail Making test B.(ABSTRACT TRUNCATED AT 250 WORDS)