Peptidoglycans (PG) from Campylobacter coli, Campylobacter jejuni, and Campylobacter fetus were composed of muramic acid, glucosamine, alanine, glutamic acid, and diaminopimelic acid in a molar ratio of 1.1:1:1.7:1.1:09. Thirty percent of the amino groups of diaminopimelic acid were involved in cross-linkages between peptides. During cultivation, C. coli and C. jejuni changed from a spiral to a coccoid form. In C. coli, we could isolate PG only from the spiral forms in yields of 0.8-1.2% by dry weight. C. fetus did not change to a coccoid form, and always contained PG. Thus, it is possible that the morphological transformation from the spirals to the coccoid forms of C. coli and C. jejuni is accompanied by, and probably due to, the degradation of PG.