Patrolling with livestock guard dogs in mountain rangelands in Norway was evaluated as a method to prevent predation in areas with widely dispersed sheep. In contrast to guard dogs, patrol dogs are more socially bonded to people and follow a range inspector around. Range inspection was performed in 5 h bouts during three nights per week. The method was tested during three summer seasons in a total of eight sheep flocks grazing in three different mountain ranges. In total, three inspectors and four dogs were involved. Significant reductions in the number of sheep lost were achieved in one of the study areas. Lack of significance in the other areas was mainly due to the size of the area and qualities of the dogs: the range to be patrolled by one man dog unit should not exceed 10-12 km2, and the dogs should be experienced guard dogs which are properly socialized for this method.