A number of technologies have been developed to study biofilm growth. Although these technologies produce reproducible biofilms for the study of biofilm growth, structure, and physiology, they have not been amenable for the routine study of biofilm susceptibility to antibiotics and biocides. For this reason, virtually every antibiotic and biocide available has been selected for activity against planktonic organisms. These drugs often have been found to lack activity against microbial biofilms. The MBEC (minimum biofilm eradication concentration) Assay System using the Calgary Biofilm Device provides, for the first time, an assay easily applicable to screening antibiotics and biocides for activity against microbial biofilms. The MBEC Assay System is ideally suited either for screening new putative antibiotics and/or biocides, or for the determination of both the MIC (minimal inhibitory concentration) and MBEC values in clinical situations for the treatment of chronic, recurrent, or device-related infections. The MBEC Assay System produces 96 equivalent biofilms formed under flow conditions, without the need for pumps. Further, as it is based on the standard 96 well platform, it conforms to existing technology available in most laboratories. The MBEC Assay System consists of a two-piece disposable plastic apparatus used for biofilm formation.