The following study describes the development of two imunoassays for the semiquantitative determination of the organophosphorus compound methyl phosphonic acid, p-aminophenyl 1,2,2,-trimethyl-propyl diester (MATP). These assays are a direct competitive, labelled-hapten, enzyme immunoassay and a competitive enzyme immunoassay with indirectly labelled antibody, both with luminescence determination of peroxidase. A camera luminometer was used to determine final signal strength. A constant light reaction was reached using luminol (5-amino-2,3-dihydro-1,4-phalazinedione), and by adding coumaric acid as an enhancer. A five minute interval was selected as exposure time. This phototechnical system makes a semiquantitative detection of MATP possible. The detection limits for both assays were at 10(-6) mol/l MATP. With the help of a microtiter luminometer (reader) the detection limit was reduced to 5 x 10(-8) mol/l MATP, by measuring the real intensity of the chemiluminescence signal.