A case of septic arthritis was caused by Enterobacter agglomerans, an association that to our knowledge has not been described previously. The right knee joint of a previously healthy 11-year-old boy became infected when the organism was introduced through the overlying skin by a contaminated wooden splinter. Conservative management with antibiotic therapy and repeated arthrocenteses was successful. Enterobacter agglomerans is a known plant pathogen, and a relationship between human infections caused by this organism and contact with plants is well recognized. The patient described here demonstrates that, when given a suitable set of environmental circumstances, E agglomerans can cause infection in man, including septic arthritis.