To determine the causes of death in Bernese mountain dogs, to assess the prevalence of malignant histiocytosis in the Danish Bernese mountain dog population, and to assess whether a hereditary pattern for this disease exists, 756 questionnaires were sent to members of the Danish Bernese Mountain Dog Club requesting information regarding the life span and causes of death of their dogs. A response rate of 57.7 per cent was achieved, giving information for 812 dogs, of which 290 had died. The average life span was 7.1 years. The most prevalent causes of death were neoplasia (42.1 per cent), old age (10.3 per cent), kidney disease (6.9 per cent), infection (5.9 per cent), skeletal problems (5.2 per cent), heart disease (3.8 per cent) and behavioural causes (3.5 per cent). Thirteen dogs were diagnosed with malignant histiocytosis, 11 of which were genealogically related.