A beta-cyclodextrin (beta-CD)-based sensor has been developed for a simple and sensitive determination of rifampicin (RIF), given in the treatment of tuberculosis (TB) and other infections. beta-CD was fixed onto a Pt electrode by means of pyrrol electropolymerization. RIF was deposited on the surface of the modified electrode through complex formation and quantified amperometrically. The experimental variables were optimized using an experimental design, taking into account all the possible interactions between them. Under these conditions, repeatability, reproducibility and stability of the modified electrode have been analysed. Interferences from other anti-TB compounds were investigated. The detection limit for RIF was 1.69 x 10(-6) mol dm(-3) (probability of false positive and negative equal to 0.05 and a replicate). The modified electrode was applied to the RIF determination in pharmaceutical preparations and biological samples. (C) 2004 Elsevier Ltd. All rights reserved.