It has been known that ginseng extract contains several polyacetylene components. But we found only two polyacetylene components in the freshly prepared ginseng extract. Long-term preservation of ginseng or ginseng extract produced many artifact polyacetylenes. The ratio of artifact/genuine polyacetylene was determined by TLC-densitometry on long-term preserved ginseng samples. The results indicated that the ratio was increased proportionally with the span of preservation.