Abstract.We describe new ion-selective electrodes for piribedil (PD) based on Bi(III)-iodide or Hg(II)-iodide piribedil ion associate complexes in a poly(vinyl chloride) (PVC) membrane with dibutylphthalate (DBP) and dioctylphthalate (DOP) as plasticizing solvent mediator. The electrodes (PD-[BiI4]/DBP, PD-[BiI4]/DOP, PD-[HgI4]/DBP and PD-[HgI4]/DOP) show nearly Nernstian response over the concentration range 2105102M of the drug. The working pH ranges were 3.16.0, 3.56.0, 3.06.0 and 3.56.4, and the isothermal coefficients of the cells were 0.00113, 0.00146, 0.00059 and 0.00120V/C for PD-[BiI4]/DBP, PD-[BiI4]/DOP, PD-[HgI4]/DBP and PD-[HgI4]/DOP, respectively. The selectivity coefficients for numerous compounds are given. The electrodes have been used for the direct determination of PD in pure form and in tablets or in biological fluids by the standard addition and potentiometric titration methods.