Enteropathogenic bacteria have been identified in 413 of 7054 patients (5.9%) with intestinal disease who were examined at the Institute of Hygiene and Microbiology, University of Würzburg (South Germany), during the period November 1975 to November 1977. Salmonella was most frequently isolated (304 cases = 4.3%), followed by Yersinia enterocolitica (102 cases = 1.5%). Cases of shigellosis (7 cases) or infections with so-called enteropathogenic serogroups of Escherichia coli (20 cases) were rarely observed. Disease due to Yersinia enterocolitica occurred in 57 male and 45 female patients. Sixty-two patients were children of less than 15 years; among them, the age-group of 1 to 3 years (31 cases) was most frequently attacked. -Mild to severe enteritis was prevalent in 84 cases. Thirteen patients developed pseudo-appendicitis or abdominal cramps without diarrhea, three of whom had appendectomies. One female patient suffered from mild diarrhea followed by fever and arthritis; in three other subjects intestinal symptoms were lacking. In the two years' period the highest incidence of salmonellosis was observed during August to October. On the other hand, most Yersinia cases occurred during September to December. At the end of the year (December 1976 and November 1977, respectively) Yersinia enterocolitica became the most important agent of bacterial enteritis. The results are discussed in view of the current Federal German Public Health Regulations.