Recently we constructed a recombinant yeast cell that expresses the human androgen receptor (hAR) and yeast enhanced green fluorescent protein (yEGFP), the latter in response to androgens. When exposed to testosterone, the concentration where half-maximal activation is reached (EC(50)) was 50 nM. Eighteen different dietary supplements, already analysed by a liquid chromatography-tandem mass spectrometry method (LC-MS/MS) for the presence of anabolic steroids, were screened for androgenic activity. Eleven samples containing at least one anabolic steroid, with a concentration that was around or above 0.01 mgunit(-1) according to LC-MS/MS, were also positive in the bioassay. Seven samples did not contain any of the 49 compounds screened for in LC-MS/MS. In contrast two of them were positive in the bioassay. Bioassay-directed identification, using the bioassay as an off-line LC-detector and LC-time of flight-MS with accurate mass measurement was carried out in these two samples and revealed the presence of 4-androstene-3beta,17beta-diol and 5alpha-androstane-3beta,17beta-diol in the first and 1-testosterone in the second supplement, showing the added value of the bioassay in comparison with a LC-MS/MS screening method alone.