Clinical features of 43 cases of invasive Eikenella corrodens infections diagnosed at National Taiwan University Hospital during a 6-year period (1993-1998) were analyzed. The clinical syndromes included head and neck infection (56%), pulmonary infection (23%), intra-abdominal infection (14%), cutaneous infection (5%), skeletal infection (2%), endocarditis (2%), and pelvic abscess (2%). Nearly two-thirds of the patients (63%) had pre-existing diseases. Malignancy (35%), especially of the head and neck, was the most common underlying illness. More than half of the patients (56%) had associated factors predisposing to invasive Eikenella corrodens infection. Polymicrobial infections occurred in 28 (65%) patients, with two-thirds of the concurrent isolates being streptococci (66%). Five cases were fatal, with four deaths directly attributable to invasive Eikenella corrodens infection. Antimicrobial susceptibility testing and molecular typing were performed on 23 preserved Eikenella corrodens isolates. Antimicrobial susceptibility testing showed that Eikenella corrodens isolates were susceptible to penicillin, amoxicillin, cefoxitin, cefotaxime, cefepime, ciprofloxacin, and imipenem. The isolates were resistant to clindamycin, metronidazole, cephalothin, and cefuroxime. None of the 23 isolates produced beta-lactamase. Random amplified polymorphic DNA patterns of the 23 isolates were different, suggesting that different clones of Eikenella corrodens caused these infections.