A methanol extract of Syzygium guineense bark inhibited intrinsic contractions of rabbit isolated ileum. The inhibition, at bath concentrations of 0.5 - 2.0 mg/ml, was dose-related but non-linear. It produced sustained hypotension in anaesthetized rats. A dose of 5 ug lowered systolic, diastolic and mean blood pressure by 16%, 22% and 17%, respectively below the pre-drug levels. Maximum effect was obtained at a dose of 40 ug when the systolic, diastolic and mean blood pressures fell by 23%, 36% and 28%, respectively below the pre-drug levels. The greater fall in blood pressure was in diastolic than systolic blood pressure. The extract caused a weaker but similar effect to isoprenaline on rabbit isolated heart. While the effect on rabbit isolated ileum supports the folkloric use of the plant as an antispasmodic, further work is required to confirm and categorize the observed pharmacological activities.