The Lifetime Reproductive Success (LRS) of an individual i.e. the number of young raised during its lifespan is an indicator of its contribution to future generations and thus a measure of fitness. Nevertheless, the LRS is hard to estimate because of the difficulty to keep track of the outcome of each breeding attempt (successful or failed and, if successful, number of young raised). We propose two new methods to estimating the LRS that takes into account the uncertainty about the reproductive status when the individuals are not detected or when the reproductive status cannot be assessed. We illustrate these two methods using roe deer reproductive histories and discuss their advantages and disadvantages.