Salmonella dublin's natural host is cattle; it may cause acute disease in calves, while adult animals may be asymptomatic carriers. In humans S. dublin is the most invasive of the zoonotic Salmonella-bacteria found in Denmark. It is much more frequently isolated from the blood than from the faeces and may give rise to serous metastatic infections in practically all organs. The number of registered human infections rose from zero to 46 per year during the period 1980-1988, but has now stabilized at a level of about 20 per year. Outbreaks have been described abroad as being caused by unpasteurised milk and cheese; in Denmark beef and cow's liver must be viewed as the dominant source of infection. The direct routes of infection are, however, unknown. Tightening of regulations for the slaughtering of animals from S. dublin infected herds, optimal hygiene in the slaughterhouses and increased cooperation between the veterinary and medical professions concerning investigation of routes of infection are necessary measures to be taken in order to reduce the number of human S. dublin infections.