Abstarct: In this study, a simple and sensitive counter current salting–out homogenous liquid–liquid extraction followed by dispersive liquid–liquid microextraction coupled with HPLC used for simultaneous preconcentration and determination of Alprazolam and Chlordiazepoxide. The solvent, Acetonitrile was used as an extraction solvent in first step and dispersive solvent in second stage. The solvent, 1-undecanol, was used as an extraction solvent. For its low density and proper melting point near room temperature. Some of parameters such as pH, first step extraction solvent volume and salt effect optimized with experimental design method. At the optimized condition, preconcentration calibration curve in range of 0.017-5.6 and 0.010-5.5 mg L-1 was linear for chlorodiazepoxide and alprazolam, also limit of detections (LOD) were 1.9 and 1.3 µg L-1 for alprazolam and chlorodiazepoxide respectively. Preconcentration factor (PF) was 99.3 for alprazolam and 104.9 for chlorodiazepoxide. Relative standard deviation (RSD) for 3 repeated measurement in 0.6, 1.5, 5.0 mg L-1 concentration were 3.3, 2.0, 1.7 for alprazolam and 1.9, 1.5, 1.5 for chlorodiazepoxide. This method was applied successfully for determination of these drugs in different real samples such as pills, urine and blood serum.