The objective of this work was to study the protective effects of salvianolic acid B (Sal B) on the dysfunctions of learning and memory induced by transient cerebral ischemia in mice. The mechanisms of its actions also were researched both in vivo and in vitro. The model of dysfunction of learning and memory induced by transient cerebral ischemia in mice was used. One trail passive avoidance tests were used to evaluate the learning and memory functions and experiments in vitro were employed to observe the antioxidative effects of Sal B. Cerebral transient ischemia would impair the function of memory in mice. In step down test. the error number and latency were 2.63 and 120.5 in control group and were 1.35 and 234.4 respectively in sham operated group (p < 0.05). In Sal B treated groups, the error number was less and latency was longer significantly than those of control group. Meanwhile. 3 and 10 mgkg(-1) of Sal B iv. reduced the malondialdehyde contents in cortex, hippocampus and striatum of cerebral transient ischemia rat ion vivo. Sal B 10--100 nmol L(-1) also inhibited lipid-peroxidation and scavenged free hydroxyl radicals in vitro. As conclusion. Sal B ameliorated learning and memory dysfunctions induced by cerebral transient ischemia. Its actions might be related to its antioxidant activity.