From January, 1979, to December, 1984, 63 Hickman or Broviac catheters were inserted into 50 high risk pediatric oncology patients (median age, 37 months). Catheters remained in place for an average of 241 days. Possible catheter sepsis and exit site infection accounted for the majority (39 of 76) of the complications of long term central venous catheterization. Neutropenia (absolute neutrophil count under 500/mm3) was associated with 70% of the catheter-related infections and 75% of the non-catheter-related infections. Catheters inserted during neutropenic episodes (23) were associated with an increased risk of subsequent septicemia (60% vs. 25%), a finding apparently related to their exposure to further neutropenia (38% vs. 16% catheter days). Of the 32 episodes of septicemia of unknown origin, 19 involved Gram-negative bacteria, 14 involved Gram-positive bacteria and 4 were caused by fungi. Five of these episodes involved multiple organisms. Staphylococcus epidermidis was the most common Gram-positive organism isolated (7 of 14). Four episodes of septicemia resolved before therapy and are considered false positive cultures. Of the other 28 episodes of septicemia, 25 (89%) were successfully treated without catheter removal including 3 episodes of fungemia and 4 of multiple organism sepsis. These data demonstrate the efficacy of antimicrobial treatment without catheter removal in the pediatric oncology population with catheter-associated infections including those associated with neutropenia, multiple organisms and fungemia.