The essential oil isolated from western Moroccan Citrus aurantium L. var. amara peel, by hydrodistillation, is analyzed by Gas Chromatography-mass spectrometry (GC-MS). Fifteen compounds representing 99.86% of total oil are identified. The predominant components in the essential oil are limonene (90.90%), linalool (2.52%), myrcene (1.51%) and β-pinene (1.41%). Being both dietary and biologically active compounds, flavonoids have attracted much attention of investigations as potent species capable of affecting various biological processes in living organisms. The total flavonoids contents of aqueous and methanolic extracts of bitter orange's peel were found to be 1.43 and 14.82 mg Equivalent Quercetin/g respectively. Furthermore, the antioxidant activity of aqueous and methanolic extracts of bitter orange's peel is measured using free radical scavenging method with DPPH•. In addition, a preliminary study of the antibacterial activity of extracts of bitter orange's peel is tested against three bacterial stains: Escherichia coli, Staphylococcus aureus and Pseudomonas aeruginosa.