Genetic analyses allowed management and conservative programmes specifically designed for biodiversity conservation purposes. To date, no information is available for the N e definition of any Italian northern pike population, because of their wide, highly fragmented, distribution. Low gene flow levels may have caused some of the health population problems emerging from professional fisheries data, underlining a marked reduction of these populations. This paper reports the first estimate of genetic N e of the Lake Trasimeno's northern pike, by means of microsatellites data, over the last four decades compared with five other significant Italian populations. N e values were evaluated through specific software and θ estimator. The N e results confirm that, despite a marked reduction between 1966 and 1997 and a less than optimal status, the Trasimeno population shows a positive trend in its health status, presumably due to proper management programmes. Considerations on the biological conservation and management of this pike population are also reported.