Abstract: Eleven chemicals were investigated for their amnestic effects in one trial passive avoidance learning-step down and step through tests in mice. Anticholinergic agents such as scopolamine and anisodine, and catecholamine depletion agent such as reserpine were shown to impair acquisition of memory in both tests. The CNS depressants, including alcohol, pentobarbital, chlorpromazine and chlorodiazepoxide, disrupted acquisition and/of retrieval processes, of which, 15～20% alcohol impaired acquisition and retrieval of mice inboth tests, but it did not elicit obvious nonspecific effects. Holoperidal, a dopamine antagonist, was shown to induce impairment of acquisition of memory in step down test, but not in step through test. Protein biosynthesis inhibitors, Cycloheximide and chloramphenical, and a RNA biosynthesis inhibitor, cafriptothecin, were found to impair consolidation of memory in step down test. Chloramphenical and camptothecin, however, elicited an amnesia of consolidation in step through test.Since nearly all of the chemicals mentioned above can induce amnesia in step down test rather than step through test, the former is recommended as a simple, rapid and Sensitive method in the study of learning and memory.