Abstract-Electromagnetic interference (EMI) has an adverse effect on the performance of electronic circuit communication systems. This study derives a series of equations to analyze the effects of the EMI induced in a conducting wire on the noise spectrum of a RC Phase Shift Oscillator (RCPSO). It is shown that the extent to which EMI affects the RCPSO depends on the interference power, interference frequency, induced power, output resistance of oscillator circuit, and parasitic capacitance. Specifically, higher EMI frequencies and amplitudes have a greater effect on the RCPSO output. The results presented in this study are in good agreement with those predicted from general EMI theory.