SPR biosensor technology continues to evolve. The recently released platform from Biacore AB (Uppsala, Sweden), BIACORE J, is designed for the routine analysis of biomolecular interactions. Using an antibody–protein A and a ligand–receptor system, we demonstrate the utility of BIACORE J in determining active concentration and binding affinities. The results from these studies illustrate the high sensitivity of the instrument and its ability to generate reproducible binding responses. The BIACORE J is easy to operate and useful in diverse applications, making SPR technology widely accessible as a research tool. Copyright © 2001 John Wiley & Sons, Ltd.