A regenerable surface plasmon resonance (SPR)-based immunosensor functioning with the indirect competitive immunoreaction of monoclonal antibody between the analyte (antigen) in testing solution and antigen-bovine serum albumin conjugate immobilized on immunoprobe provided a rapid in situ estimation (response time: about 15 min) of benzo(a)pyrene in the concentration range of 0.1-300ppb.