The total noise power at the input of a radio receiver is the sum of the Additive White Gaussian Noise (AWGN) generated within the receiver referred to its input plus the antenna noise plus the available noise power at the receiver’s input due to the presence of in-band spurious, harmonics and other interferences present in the communication channel. Hence, the in-band spurious components (both in terms of their numbers and amplitudes) at the receiver input will cause a reduction in the input Carrier to Noise Ratio (CNR) of the receiver when the receiver is operating at a certain operating point.  This reduction in input CNR) i.e., the increase in input noise level will cause a reduction in the output signal to noise ratio in an analog receiver and an increase in Bit Error Rate (BER) in a digital receiver.   In this paper, an analytical model has been presented to compute the degradation in receiver’s performance or receiver’s sensitivity (i.e., the increase in input noise level) due to the in-band spurious under different situations.  The model is verified experimentally by measuring the performance degradation of a 720 MHz 8PSK receiver (with a bit rate of 480 Mbps) under the presence of in-band spurious of different amplitudes.  A close comparison between the measured data and the estimated data indicates that the analytical model presented here is good enough to estimate the effect of in-band spurious on a radio receiver.