In a 16 weeks open label therapeutic trial, studies were performed on isradipine (Lomir) to evaluate its haematological and biochemical safety and hypotensive capacity in the management of adult black hypertensive patients. The mean sitting diastolic blood pressure decreased from 105.5 +/- 9.66 mm hg at the end of the washout period to 92.1 +/- 7.59 mm hg at the end of the study, p less than 0.0001; while the mean standing diastolic blood pressure was 108.0 +/- 7.10 mm hg and 93.9 +/- 8.4 mm hg at the end of the washout phase and at the completion of the therapy respectively, p less than 0.0001. The corresponding mean sitting systolic blood pressures were 155.4 +/- 9.91 mm hg and 140.6 +/- 9.47 mm hg, p less than 0.001 while the corresponding mean standing systolic blood pressures were 156.6 +/- 12.50 mm hg and 142.6 +/- 9.15 mm hg, p less than 0.001. There were negligible changes in the mean heart rate; from 79.5 +/- 9.23 beats per minute (bpm) at the end of the placebo phase to 78.2 +/- 9.15 bpm at the end of the study in the sitting position, p greater than 0.1. The corresponding mean standing values of heart rate were 82.5 +/- 11.33 and 78.6 +/- 8.76, p greater than 0.5. The haematological, biochemical and electrocardiographic parameters remained within normal limits during the study. Side effects were mild, transitory, improved with therapy and consisted of dizziness, palpitations, headache, nocturia, tiredness and fainting attacks. The study achieved 96% good-to-excellent results with respect to both efficacy and tolerability. Isradipine (Lomir) is therefore an efficacious and safe antihypertensive agent in the management of black adult patients with mild to moderate primary arterial hypertension when administered in the dose of upto 2.5 mg twice daily alone or in combination with a beta-blocker.