The concentration of anionic polyelectrolytes was indirectly evaluated from the electrode oxidation of a ferrocenyl group of the title cationic surfactant, which adsorbed at a carbon paste electrode (CPE) to associate with anionic polyelectrolyte. The adsorptive ion-association complex between anionic polyelectrolyte and the ferrocenyl cationic surfactant was accumulated at the electrode in the absence of an applied potential. The adsorption wave which appeared in the voltammogram at CPE was larger than that at a glassy carbon electrode, and the peak current was observed at a more positive site than that for the voltammogram of only ferrocenyl cationic surfactant in 0.1 mol dm-3 NaCl solution. A second adsorption wave, which appeared in the measurement of an anionic surfactant using the ferrocenyl cationic surfactant, was not obtained. After 10 min of accumulation, the level of heparin of 10-6 eq. mol dm-3 could be measured by a linear relationship between the concentration and the peak current. The dependence of peak current on the concentration of poly(styren sulfonate), however, was not linear. In addition, the peak current decreased with the concentration at a high concentration. The relative standard deviation for each peak height was less than 5.4% for heparin and 5.8% for poly(styren sulfonate) in five runs.