Teucrium chamaedrys L. (Labiatae), a herb used to combat obesity, can occasionally cause hepatitis. All mutagenicity tests done were negative. After 13 weeks of administration by oral route in Sprague Dawley rats T. chamaedrys proved to be well tolerated at 0.056 g kg(-1) day(-1) (i.e. 0.4 mg kg(-1)