Objetive: We evaluated with 24 hour ambulatory blood pressure monitoring (ABMP) throughout 24 hours the combination of long acting verapamil once a day plus captopril twice a day (V + C) in moderately-severely hypertensive patients. We also compared choice of dosage between office blood pressure (OBP) and ABMP using this combination therapy. Design and methods: In 21 hypertensive patients who did not respond previously to monotherapy -aged 37-67 y.o., 13 males and 8 females- we meassured OBP and 24-hour-ABPM alter a washout period (PO) and at 4 (PA), 8 (PB) and 12 weeks (PC) with a combination oi V + C. The dossage was: V + C, 240 + 50 mg during PA, ii diastolic OBP was > 89 mmHg it was increased to 360 + 50 mg at PB, and to V + C 360 + 100 mg at PC. Results: OBP al PO in mmHg were: 172 +/- 16/120 +/- 11; at PA 149 +/- 19/102 +/- 9; al PB 144 +/- 24/98 +/- 11, and al PC 142 +/- 23/97 +/- 9, (p < 0.01, ANOVA). Diurnal ABP in mmHg al PO were: 159 +/- 19/107 +/- 11 at PA 141 +/- 23/94 +/- 11, at PB 140 +/- 21/89 +/- 11, and at PC 139 +/- 20/89 +/- 11, (p < 0.01, ANOVA). The number oi patients controlled according to OBP and ABP were at PA: 1/7, at PB: 3/11 and PC: 5/8. Chi square test was significant only when comparing OBP and ABP al PA and PB (p < 0.05). Conclusion: We observed the most important decrease in blood pressure between periods with the initial dosage oi the combination V + C (240 + 50 mg) at PA. However, ABPM showed the best efficacy oi V + C at PB (360 +/- 50 mg). Increasing dosage did not achieved better control oi blood pressure. On the contrary according to the office blood pressure we increased dossage in every period. Thus there is a difference between office blood pressure and diurnal blood pressure monitoring which makes selection of patients and decision of final results different with each method used.