Electron spin resonance (ESR) investigations on blends of polyaniline (PANI) and polyvinylchloride (PVC), containing different amounts of PANI, ranging from 0 to 40% (in weight), are reported. The temperature dependence of resonance line parameters, in the temperature range 150 K to 500K is analyzed. It is proved that the high spins bipolarons are not contributed to the ESR spectrum and that the resonance spectrum does not contain contributions due to extremely high conducting islands, with lengths of the order of at least 1micron. From the temperature dependence of the double integral of the resonance line, it is concluded that, the blends exhibit an almost pure paramagnetic behavior and that at short times physical processes control the behavior of these blends. At long times (102 to103 hours), the resonance spectrum is drastically reduced due to the consumption of free electrons in the chemical reactions involved by the degradation processes occurring mainly in PVC. A stationary value is reached for storage times of about 2500 hours, in air, at room temperature.