We conducted a survey on the causes of moose (Alces alces) deaths at 19 European moose facilities. The age at death was recorded for 205 moose, and the cause of death for 131 adult animals. The "wasting syndrome complex" (WSC) [Shochat et al., 1997] was the single most important mortality factor in adult animals, being responsible for 47% of all cases. Other important factors were intraspecific aggression (13%) and malignant catarrhal fever (12%). The number of deaths showed a peak at the age of 6-8 years. A similar peak was found in the age distribution of WSC cases only, suggesting an accumulative process that leads to the death of an animal once a threshold is reached. While the dominance of WSC is in accord with the American literature, the high incidence of intraspecific aggression found in this and other European surveys is not reported in North America. While in the North American literature the consumption of grass and grass products is regarded as the main factor triggering WSC, infection with whipworms (Trichuris spp.) and continuous reinfection through pasture grazing is emphasized as the main danger in Europe. Most reports of WSC in the literature concern animals that grazed in pasture-like enclosures. In no case was WSC triggered by controlled feeding of freshly cut grass fed to animals in holding pens. In our survey, in half of all documented WSC cases Trichuris infestation was reported as well. With a high proportion of incomplete necropsies in our data set, we suggest that the contribution of Trichuris to the problems of moose husbandry has been underestimated.