Over a seven-year period (2001-2007) flocks of four poultry species, 52 broiler flocks, 46 Pekin duck flocks, 22 Muscovy duck flocks, 20 turkey flocks, which were kept on the same farm, were continuously investigated for Campylobacter (C). Altogether 76.1% of the broiler flocks, 59.6% of the Pekin duck flocks, 68.2% of the Muscovy duck flocks and 90.0% turkey flocks were Campylobacter positive. The prevalence during the course of the fattening period increased steadily. There was no specific point of time for the onset of infection. More detailed examination over a one-year period showed the highest isolation rates of C. coli from July to September and a higher isolation rate of the same agent with increasing age, in all species except Muscovy ducks. Moreover, C. coli was isolated more often from the lungs of broilers and Muscovy ducks than from the other two bird species. Flocks of all species housed during the summer months featured a higher prevalence of Campylobacter colonisation than those housed in winter. This was statistically significant for broilers. Another approach for evaluating the seasonality of Campylobacter colonisation was to compare the age of the respective poultry species when the onset occurred in summer and in winter. All poultry species were younger when infection was introduced into a flock in summer. This was statistically significant for broilers and for Pekin ducks.