The presence of Staphylococcus aureus in positive blood cultures could be rapidly confirmed by the use of a commercial test kit (Rapidec Staph; bioMérieux, France) that detects coagulase in the culture broth after 2 h of incubation. This kit detected all 35 Staphylococcus aureus strains from 117 blood cultures with gram-positive cocci growing in clusters. The sensitivity and the specificity of the technique were 100% and 98.8%, respectively. The Rapidec Staph kit appears to be a simple and reliable technique for the rapid detection of Staphylococcus aureus in blood cultures.