We studied forty-seven anaerobic strains recovered from blood cultures or pus from deep infections over three months. Antibiotic sensitivity was tested using two dilution techniques. For both, a standardized, controlled inoculum was used and strains with known susceptibilities were included. The first method consisted of dilution of antibiotics in Schaedler broth and MIC determination using microplates. In the second method, dilutions in Wilkins-Chalgren broth with 1.5 g/l agar and ATB-API plates were used; these plates are specially designed for anaerobes and have not yet been marketed. Advantages of dilution techniques for antibiotic sensitivity testing of anaerobes are recalled. Our findings establish that, under correct technical conditions, results of both methods studied are consistent.