Gram-negative bacteremia is usually transient, especially when appropriate antimicrobial therapy has been instituted. The identification of twenty patients with persistent gram-negative bacteremia led us to re-examine the special implications of this condition. Bacteremia was considered persistent if blood cultures were positive for the same organism(s) repeatedly over a period of at least seven days and bacteremia persisted for at least three days after institution of appropriate antimicrobial therapy. The sources of bacteremia included intra-abdominal abscesses of gastrointestinal origin in eight patients and of renal origin in four. Intravascular infection was the source of bacteremia in three patients and served to perpetuate bacteremia in five. Other causes included lung abscess in two patients, contaminated intravenous fluids in one, and an infected amputation stump in another. The Klebsiella-Enterobacter group accounted for eleven of the twenty episodes of chronic bacteremia, and polymicrobial bacteremia occurred in ten patients. The over-all mortality was 55 per cent and was less if surgical drainage was successful. Persistent gram-negative bacteremia is usually the result of cryptogenic gastrointestinal or genitourinary tract suppuration and, when diagnosed, should encourage careful attention to appropriate antimicrobial therapy and early surgical intervention. The possibility of intravascular infection as causal or exacerbating factor should be considered. Illustrative cases are reported which serve to reinforce these recommendations. © 1973.