The effects of ethylacetate extract of red onion (Allium cepa) tunic (ACTE) on some hemodynamic and biochemical parameters were evaluated in normotensive albino rats. Blood pressure parameters were determined in anaesthetized rats orally administered ACTE (10-, 20-, or 40 mg/kg) or ramipril (1 mg/kg) once daily for 14 days. Respectively, 10-, 20-, or 40 mg/kg ACTE produced significant (P<0.01), dose-dependent fall in systolic blood pressure, SBP (21%, 27%, 33%), diastolic blood pressure, DBP (6%, 10%, 16%), pulse pressure, PP (42%, 49%, 56%), mean arterial blood pressure, MAPB (13%, 18%, 23%) and heart rate, HR (4%, 5%, 7%). The highest effective dose (40 mg/kg) compared well with ramipril (1 mg/kg) with regards to SBP (41%), DBP (19%), PP (70%), MABP (29%) and HR (10%). Similar trends (decreases) were recorded for 40 mg/kg ACTE and ramipril, respectively, as regards the activities of serum enzymes: creatine kinase (60% and 65%), ALT (18% and 14%) and ALP (28% and 16%). HPLC fingerprints of the flavonoid-rich ACTE revealed that flavonols: quercetin, quercitrin, isoquercitrin, rutin and kaempferol are the active flavonoids. The results demonstrate the hypotensive effect of A. cepa tunic flavonoids initiating further investigation of their individual or synergistic contribution(s) to the observed effects.