A sensitive method has been studied for the determination of codeine phosphate in water samples using dispersive liquid-liquid microextraction coupled with Uv-visible spectrophotometry. Parameters that affect on the extraction efficiency, such as kind and volume of the extraction and disperser solvent, extraction time, salt addition were investigated and optimized. Under the optimal conditions, the linearity of the method was obtained in the range 0.005-10 μg/mL with coefficient of (r2) 0.9996. The limit of detection and relative standard deviation were 0.001 μg/mL (n=7) and 2.85 (c=2 μg/mL, n=5) respectively. Also, the proposed method was applied to the determination of codeine phosphate in water samples with satisfactory analytical results.