Twenty drugs of plant origin were analysed in order to determine the microbial contamination level. A light homogenizing method was used to avoid an increase in the antimicrobial capacity of certain drugs, which would falsify the analytical results. The total viable aerobic count (TVC) varied from 10(1) to 10(7) CFU/g and in 11 samples out of 21 was equal to or higher than 10(5) CFU/g. The number of fungi varied from one drug to another, but was generally lower than the aerobic TVC to the power of 10. No cases containing Aspergillus flavus were found. The total viable anaerobic count consisted mainly of facultative anaerobic germs. Aerobic spores and facultative anaerobic bacteria were abundant. They often represented more than 50% of the aerobic TVC and among them, Bacillus cereus was found. Concerning specified micro-organisms, Escherichia coli was found 3 times, Staphylococcus aureus 2 times and Pseudomonas (not aeruginosa) a few times. Salmonella was never found. The Enterobacteriaceae, on the other hand, were often found and in some cases their number can be greater than 10(4) CFU/g. The typed bacteria corresponded to Enterobacter spp. Some drug samples in bags were analysed. The level of contamination was identical to that found in the bulk drugs. The analysis in parallel of a black tea sample showed an aerobic TVC of 4.10(3) CFU/g. Specified micro-organisms were not found in the infusions. In comparison with non-boiled drugs, the survivors can represent up to 30% of the aerobic TVC.