The genome of Campylobacter jejuni was characterized by field inversion gel electrophoresis (FIGE) after digestion with three rare-cutting restriction endonuclease. The restriction enzymes Sac II (5'-CCGCGG), Sal I (5'-GTCGAC), and Sma I (5'-CCCGGG) were found to produce 13, 5, and 8 fragments respectively from the C. jejuni genome. The fragment sizes ranged from 1.6 kb to 1300 kb, which gave C. jejuni a genome size of approximately 1900 kb. Furthermore, the gly A and rRNA genes of C. jejuni were localized to specific fragments by use of Southern analysis, and the gly A gene was shown to be closely linked to one of the three rRNA genes.