The series resistance (RS) of Junctionless Nanowire Transistors (JNTs) with different doping concentrations was extracted from 473 K down to 100 K. The source/drain parasitic resistance presented by JNTs was compared to the one presented by classical inversion mode (IM) triple gate devices and the impact of the series resistance on the drain current of the devices was evaluated. The RS analysis was carried out through experimental results and devices tridimensional numerical simulations. According to the study, RS presents opposite behavior with the temperature variation in IM triple transistors and JNTs. In the latter, a reduction on RS is noted with the temperature increase, whereas a resistance decrease is obtained with the temperature lowering in IM devices. The parasitic resistance in JNTs affects the drain current in such a way that there may not be a Zero Temperature Coefficient (ZTC) operation point.