Prevalences of diseases in purebred dogs are reported from a questionnaire study among members of the Danish Kennel Club (DKC) in 1997. The 4295 dogs in the study represented 24 breeds and 16 breed groups. Sixty percent of the dogs had at least one disease-event during their lifetime with a median of 2 and a maximum of 11. Diseases of the skin were the most-frequent (13.6%) followed by eye diseases (13.2%), accidents (12.6%) and diseases of the ear (12.6%). The prevalences of five diseases differed significantly between the breeds (diseases of the skin, eyes, ears, respiratory and skeletal systems). Males had significantly higher prevalences of respiratory diseases, skeletal diseases and diseases of the mouth and teeth. Tumours and diseases of the urinary system were most prevalent in females. Gender- and breed-specific prevalences are reported for the most-frequent diseases.