Abstract: Sumac is the common name for Rhus genus and various species have been used for medicinal and food purposes. In this study, a solid-liquid extraction method was used to extract polyphenols from Syrian sumac (Rhus coriaria L.) and Chinese sumac (Rhus typhina L.) fruits. Various experimental conditions such as ethanol concentration in water (0-100%, v/v), extraction time (1-9 h), extraction temperature (20-60°C), particle size (0.5-2.5 mm) and solvent to sumac ratio (5:1-25:1 mL g-1) were investigated to optimize the extraction. The amount of polyphenols was measured by Folin-Ciocalteau procedure to monitor the efficiency of extraction. The optimal extraction conditions were found to be similar with both sumac species except for the extraction time, with Syrian sumac requiring 1 h and Chinese sumac 5 h; ethanol concentration (20%, v/v); extraction temperature (40°C); particle size (1.0 mm) and solvent to sumac ratio (15:1 mL g-1). In addition, extraction time and ethanol concentration were the most significant processing parameters with Syrian and Chinese sumac fruits, respectively. Under optimal conditions, the polyphenols content was 159.32 and 150.68 mg gallic acid equivalent per gram of extract with Syrian and Chinese sumac fruits, respectively. The present findings showed that polyphenols can be extracted from sumac fruits using the solid-liquid extraction method which is efficient, safe and less costly.