This paper proposes a new approach to accurately evaluate the reliability of future nano-circuits. The proposed approach combines the accuracy and intuitiveness of Monte Carlo (MC) simulation with the simplicity and high modeling capacity of numerical simulations. This approach is important and timely as the expected size of future nano-circuits will make the exclusive usage of MC simulation timely prohibitive. At the same time, simulation methods that depend solely on numerical simulations are unfortunately not accurate enough. Experimental results show that the circuit reliability calculated by the proposed approach is very close to the reliability calculated based on MC simulation only. Index Terms - Reliability evaluation, nano-circuits, Monte Carlo, Bayesian networks, numerical methods.