With the proliferation of bioinformatics web services, innovative on-tology based frameworks have been developed to allow an efficient service discovery process, but they do not provide semantic annota-tions regarding services availability and reliability. To fill this gap, and because the quality of service is a major factor that limits the success of promising service oriented architecture in bioinformatics, we created QBIOS, an automatic test engine dedicated to bioinfor-matics services. QBIOS allows service test case creation, scheduled execution and distributed monitoring. It provides reliable quality of service indicators that can be used in workflow management sys-tems and shared to build community based service repositories and trustable searching engines.