Campylobacter sp. have an important role in the etiology of contagious enteritis of dogs, other species of animals, but also of humans. Animals that excrete this bacterium by feces are a source of infection for other animals and humans. Campylobacteriosis is zoonoses, a disease that is transmitted to humans from animals and animal products. Although poultry and cattle are considered the main source of disease, the source can be feces of dogs and also bacterium can be excreted by healthy dogs. The source of the infection in dogs is contaminated food, water, environment, contact with feces of infected animals and the infection spreads faeco oral way. Factors of the risk of infection in dogs are exposure to water retention and life in agglomerations such as asylum and kennel that makes it easier to spread the infection. The higher incidence of clinical manifestation of disease in puppies and young dogs is most likely a consequence of weaker immune system development. Clinical illness is manifested by nonspecific signs of gastroenteritis, and the infection may be subclinical when animals excrete Campylobacter sp. by faeces. Campylobacteriosis is the leading bacterial zoonosis associated with food poisoning in European Union countries, while in Croatia in the first place is salmonella, but campylobacteriosis is in the second place. The aim of this study was to establish and compare the frequency of separation of campylobacter from healthy dogs and dogs with diarrhea, to determine and compare the frequency of campylobacter isolation within age groups and to identify the type of isolated campylobacter. 26 In the study of the rate of excretion of bacterial strains of Campylobacter in dogs, 70 dogs with diarrhea and 70 healthy dogs were included and were divided into two age groups: younger than one year and older than one year. Out of a total of 140 examined samples of feces, 36.4% tested positive. In the group of dogs with a diarrhea, 67.1% was positive and in the group of healthy dogs 5.7%. It is significantly more common in dogs with diarrhea than in healthy dogs (p <0.01). In the group of healthy dogs it is more commonly isolated from dogs under the age of one year (p <0.01). In dogs with diarrhea there was no difference between the age groups. All stored isolates of dogs with diarrhea were identified by the MALDI-TOF method as C. jejuni species. The results of the study suggest that the incidence of Campylobacter sp. shedding in dogs is high, especially in diarrheaic dogs. Within the group of healthy animals, a higher incidence of shedding has been found in dogs under one year old. That should be kept in mind, especially when animals come into contact with children or immunocompromised people