The objective of this study was to assess the safety and efficacy of 1.25 to 2.5 mg of isradipine twice daily in patients with mild-to-moderate hypertension, as seen in general practice. A total of 595 patients were treated for 6 months with an initial dose of isradipine at 1.25 mg twice daily. This dose was doubled if normotension (diastolic blood pressure [DBP] < or = 90 mm Hg) was not achieved after 4 weeks of treatment (n = 327). If, after 8 weeks, blood pressure was still not normalized, either the angiotensin-converting enzyme (ACE) inhibitor spirapril at 3 mg (n = 58) or the beta-blocker pindolol at 5 mg (n = 54) was added to the treatment. After 24 weeks, the mean blood pressure decrease with isradipine at 1.25 mg twice daily was 28.5/19.0 mm Hg for systolic blood pressure (SBP)/DBP and, with 2.5 mg isradipine twice daily, 28.4/18.5 mm Hg. There was no relevant change in heart rate. The overall normalization rate for all 595 patients was 78.2%. Side-effects that were considered related or possibly related to treatment were reported in 73 patients (12.3%). Treatment with isradipine plus either spirapril or pindolol was discontinued in 32 patients (5.4%) because of side-effects related, or possibly related, to the study treatment. Blood pressure was also self-recorded in a subgroup of 45 patients. The self-recorded values were 11/6 mm Hg (SBP/DBP) lower than the respective causal readings at the start of active treatment. However, this difference disappeared completely after 8 weeks of treatment.