The present work relates to the development and validation of reversed-phase HPLC-UV-photodiode array methods for the estimation of two drugs in blood serum: dronedarone hydrochloride (DDN), a class III antiarrhythmic drug, and duloxetine hydrochloride (DLX), an antidepressant. Chromatographic analysis of DLX was carried out on a Nucleodur C18 column (250 × 4.6 mm, 5 μm) using ammonium acetate buffer (32 mM, pH 5.5) and acetonitrile (40 + 60, v/v; flow rate of 1.0 mL/min; detection wavelength of 290 nm) as the mobile phase. A Waters XTerra C18 column (250 × 4.6 mm, 5 μm) was used for the chromatographic analysis of DDN using an acetonitrile-ammonium formate buffer (20 mM, pH 3.0, with formic acid; 45 + 55, v/v; flow rate 1.0 mL/min) as the mobile phase. Pentazocine and bupropion HCl were used as the internal reference standards for DLX and DDN, respectively. Excellent linearity was observed for DLX (r2 = 0.9996; concentration range 0.2-10.0 μg/mL) and DDN (r2 = 0.9997; concn. range 2.0-50.0 μg/mL). The LODs for DLX and DDN were 0.022 and 0.78 μg/mL, respectively, and the LOQs 0.066 and 2.4 μg/mL, respectively.