A novel binary typing (BT) procedure, based on reversed hybridization of digoxigenin-universal linkage system-labeled bacterial DNA to strip-immobilized probes, is presented. Chromogenic detection of hybrids was performed. Staphylococcus aureus isolates (n ‫؍‬ 20) were analyzed to establish the feasibility of BT. A technically simple and fast procedure has been developed for application in routine microbiology laboratories.Reliable probe-based microbial typing systems are not yet commonplace in microbiological practice (1,4,7,8,12). In the past we identified domains that are differentially present within the staphylococcal genome on the basis of randomly amplified polymorphic DNA analysis. These probes were used to develop a DNA probe-based typing approach. The strain-specific DNA probes provide a simple binary output and have been presented before (13-15). We describe here the development of a new format for the binary typing technique. In the newly described procedure DNA is extracted from overnight Staph-