To assess how important reindeer Rangifer tarandus fences are as a mortality factor for ptarmigan Lagopus spp. we collected data during 1991–1994. Our fieldwork covered 12 different sections of reindeer fence (totalling 71.1 km) in the county of Finnmark, northern Norway. The sections consisted of steel wire, steel netting or a combination of these, and ranged in height from 100 to 250 cm. The fieldwork took the form of spring patrols during which dead birds and their remains were searched for along the fences immediately after snow melt. We covered a total of 179.9 km and found 253 collision victims belonging to at least 20 species. Of the 253 victims found, 215 were willow ptarmigan Lagopus lagopus and rock ptarmigan L. mutus; thus these two species comprised 85% of the victims. During the winters of 1992/93 and 1993/94, we carried out experiments with dummy willow ptarmigan which were placed along fence sections and monitored serving as artificial fencestrike victims. Our experiments showed that approximately 64% of the total number of ptarmigan killed by the fences during winter would be detected during spring patrols along the fences. The type and height of the fence had no effect on the ptarmigan collision rate. In contrast, both the fence section and year factor contributed significantly to the observed variation in collision rate. We estimate that on average 1.4 ± 0.5 (SE) ptarmigan are being killed per kilometre of reindeer fence in Finnmark annually, with a greater variation between fence sections than between years.