The objective of this work is to characterize the wastewater from the Sidi Slimane slaughterhouse (Morocco) with a view to recommending an adequate treatment. This wastewater is discharged into Wadi Beht, which is one of the main tributaries of Wadi Sebou, without prior treatment. The physicochemical analyzes of the raw wastewater collected at the outlet of the slaughterhouse reveal that this water is loaded with organic matter expressed in terms of SS (603.6 mg /l), COD (10,607.048 mg /l) and BOD5 (4284 mg /l) and in mineral matter determined by measuring a certain number of parameters: conductivity (1441 μS /cm at 20°C), total phosphorus (35.31 mg/l), total nitrogen (377, 96 mg /l) and nitrates (4.17mg /l). Analyzes of samples taken from slaughterhouse wastewater mixed with domestic wastewater, at the point of discharge into Wadi Beht show a dilution of the concentrations. Despite the load of this wastewater, it is noted that the values found remain below the accepted standards. Examination of the COD/BOD5 ratio clearly highlights the biodegradable nature of the wastewater from the slaughterhouse in the town of Sidi Slimane, for which biological treatment seems quite suitable.