Eight healthy female volunteers were included in a double-blind, cross-over trial comparing Ginkgo biloba extract in acute and ascending doses (120, 240, 600 mg) with a placebo. One hour after treatment they were subjected to a battery of tests, including: critical flicker fusion, choice reaction time, subjective rating scale and Sternberg memory scanning test. No statistically significant differences with the placebo were observed in the first three tests. In contrast, short term memory, as assessed by the Sternberg technique, was very significantly improved following 600 mg of Ginkgo biloba extract, as compared with the placebo. These results differentiate Ginkgo biloba extract from sedative and stimulant drugs and suggest a specific effect on memory processes.