Overhead conductors are considered critical assets in power systems. Hence, with the assessment of conductor condition, the asset owner can improve decision-making about maintenance or replacement plans. Commonly, these plans involve high investments. This paper presents a methodology to assess the condition of overhead line conductors by computing Health Index. The parameters that influences on the Health Index calculation are addressed. In order to assess the conductors, the Rate of Failure, Reliability and Probability of Failure are calculated with an estimated Health Index changing over time. The estimation model can be fitted according to historical data. Finally, the influence of maintenance on the conductor's condition is simulated.