We report an isocratic, HPLC procedure for assay of the orally administered hypertension drugs [atenolol, amlodipine, nifedipine, nitrendipine, nimodipine and felodipine given in retention order] of which atenolol, an aryloxypropanolamine β-blocker is administered with anyone of the other five dihydropyridine calcium channel blockers in combined hypertension therapy. The drugs were dissolved in methanol and 20 μl of a mix of the drugs was injected onto a reverse phase JASCO-metaphase ODS (250x4.0 mm) 5 μ column. Any one of the six drugs could be used as the internal standard. The drugs were resolved by elution with a pH 4.5 equivolume mobile phase of acetonitrile-0.01 M KH 2 PO 4 , with pH adjustments done with H 3 PO 4 (flow-rate 1.5 mlmin - 1 ). The column effluent was monitored at 250 nm. The detector response (peak height ratio) was linear in the dynamic range of 25-3200 ngml - 1 of these drugs, with the detection limits at ~15 ngml - 1 . Full statistical evaluation of the data including linear regression (least-square fit) analysis was performed. The suggested procedure has the advantage that all the five dihydropyridine derivatives can be quantified alone or in formulation with atenolol.