Reliability of electronic systems has been thoroughly investigated in literature and a number of analytical approaches at the design stage are already available via examination of the circuit-level reliability effects based on device-level models. Reliability estimation during operational life of an electronic system still lacks a solution especially for analog and mixed signal systems. The current work will present a novel technique for indirectly estimating reliability during operational life of an electronic system. Reliability simulations during the design stage of a potential critical performance parameter, sensitive to aging effects, over a range of input-stress voltages and working-stress temperatures have been used to generate a set of degradation values per unit time. These values are then used at the system level to estimate the degradation in that particular performance parameter and hence system reliability by regularly monitoring the input-stress voltages and working-stress temperatures. The simulation results conducted for an example target system in a LabVIEW environment show that the proposed technique is viable.