Because of the evolution of the reliability of electronic circuits toward very low failure rate, the statistical analyses through accelerated ageing experiments become too expensive. Today, a deterministic approach of the physics of failure is necessary to estimate the life duration of the circuits. As the ageing mechanisms are highly dependent on the circuit operating conditions, electrical simulation is a very useful tool to help the assessment of the degradation effect. This paper will present on the basis of a practical case the advantages to use a behavioural modelling language like VHDL-AMS for the simulation of ageing of electronic circuits and an original approach for the simulation of the ageing of complex systems.