In the northern part of Finland we have about 450,000 reindeer and their raising gives work to about 3,500 reindeer herders. In this study data on the occupational accidents of herders were collected by two questionnaires with an interval of 2 years. Based on the surveys of accident risks in various work phases 34 preventive measures were developed and information about them was passed on to the herders between the questionnaires. Most of the accidents occurred in the late autumn during slaughtering, gathering for separation and during separation work. The main causes of accidents were the slaughtering knife (30%) and the reindeer itself (25%). The most serious accidents were caused by snowmobiles and other terrain vehicles. The recommended preventive measures mostly dealt with the environment of permanent working places, personal protection and working habits. The follow-up questionnaire showed that the herders had implemented on an average 5.8 preventive measures. The incidence rate of accidents also decreased during the 2 years from 21 to 12 accidents/1000 working days. In conclusion these results show that it is possible to develop measures preventing accidents and to improve the safety in reindeer herders' work.