A fluorescence polarisation immunoassay (FPIA) for the screening of sulphamethazine (SMZ) in chicken muscle was developed. Fluorescein-labelled tracers for several sulphonamides were synthesised and monoclonal antibodies (Mabs) and polyclonal antibody (Pab) were produced. The Mabs and Pabs were raised against sulphonamides conjugated to bovine serum albumin by a diazo method. The most sensitive FPIA method for SMZ detection was based on a combination of the Mab against SMZ–bovine serum albumin and tracer SMZ labelled with fluorescein isothiocyanate. The limit of detection and IC50 for SMZ were 1 and 16 ng mL−1. Recoveries of SMZ from fortified chicken muscle samples averaged between 78% and 89%. The proposed FPIA method was applied for determining SMZ in an actual residue study.