the investigation allegedly showing many samples of the store brands of gingko biloba and st. john's wort at wal-mart, walgreens, target and gnc did did not contain any of those herbs. samples of the store brands of ginseng and echinaecea failed ingredient tests at wal-mart, walgreenss and gnc. >> the fda is not scrutinizing the supplements in any way, near to what they are doing with drugs. >> 400 tests were conducted. 79% of the samples contained none of the product labelled or they were con tham tam nated. >> it's becoming like a guessing game. gee, i hope it is in the bottle but it turns out more often than not it isn't. >> reporter: gnc says it stands by the products and the tests used may not be appropriate for these herbal products. wal-mart said it is reaching out to the suppliers and will take appropriate action. target telling us it is committed to providing high-quality, safe products. but walgreens says, they are now in the process of removing these products as we review this matter further. experts say the real concern,