Illegal harvesting of wildlife is a global issue. Illegal killing is the major threat to recolonizing wolf (Canis lupus) populations. In Northern Europe, poaching is focused on wolves that have the biggest conflicts with human. Poaching is largely a hidden criminality and is difficult to measure. The wolf population in Finland has fluctuated between 100-300 during the past 20 years with no known reason. We examined the role of poaching on wolf population changes. We created different scenarios to detect the effect of poaching on population level. Data consisted data of 130 tagged wolves from the period 1998-2014. Illegal killing and legal hunting were the most common causes of mortality. Social status of the wolf had a significant relation to their fate. Breeding adults had the highest risk of being killed illegally. Poaching risk had a clear seasonal trend and survival dropped steeply in mid-winter. Poaching rate varied considerably between the years. Further, we modeled the predictors of illegality of a wolf kill using data from 76 GPS-collared wolves on two spatial scales. According to our results, poaching has regulated the Finnish wolf population that is simultaneously legally harvested. Legal hunting on local and country-wide scales decreases poaching risk, whereas an increasing trend in quota and detectability increase poaching risk. Legal hunting seems to decrease poaching in the short run but does not increase the tolerance as such. Our results provide useful knowledge for conservation, management and law enforcement.