The MICs of 24 antimicrobial agents were determined for 335 strains of Yersinia enterocolitica isolated from faeces in the Netherlands during 1982-1991. The isolates belonged to biotypes 1A, 1B, 2, 3, 4 and to serotypes O3, O5.27, O6.3, O7.8, O8, O9. Almost all strains were susceptible to piperacillin, piperacillin/tazobactam, imipenem, all cephalosporins except cefazolin, the aminoglycosides, quinolones, co-trimoxazole, doxycycline and chloramphenicol but resistant to amoxycillin, co-amoxiclav and macrolides. No association was observed between susceptibility patterns, biotype or serotype nor were there marked changes in the susceptibility during the last decade. The agents traditionally used to treat human infection, including co-trimoxazole, doxycycline and chloramphenicol may remain drugs of first choice.