A multicentre, randomised, double-blind, cross-over comparison of nifedipine GITS 20 mg once daily and nifedipine retard 10 mg twice daily in 49 patients with mild to moderate hypertension was conducted. Both treatments resulted in clinically significant trough blood pressure reductions (nifedipine GITS -10.1/-8.9 mmHg, nifedipine retard -7.5/-8.2 mmHg). The study demonstrated that nifedipine GITS was 'at least equivalent' to nifedipine retard in the reduction of trough diastolic blood pressure tone-sided lower 95% confidence limit, -1.2 mmHg). The overall incidence of adverse events (nifedipine GITS 25.5%, nifedipine retard 34.0%), as well as the incidences of headache (nifedipine GITS 8.5%, nifedipine retard 12.8%) and peripheral oedema (nifedipine GITS 2.1%, nifedipine retard 8.5%), was higher with nifedipine retard compared to nifedipine GITS. Nifedipine GITS 20 mg once daily is 'at least equivalent' to nifedipine retard 10 mg twice daily in patients with mild to moderate hypertension, as well as being better tolerated.