Forty nine Broviac or Hickman indwelling central venous catheters were inserted in 36 patients with haematological and neoplastic diseases for indications including young age, intensity of treatment, and psychological attitude. Sixteen patients suffered 29 episodes of infection related to the catheter bacteraemia (0.68 episodes per 100 days of catheter use). Infections occurred much more commonly where there was intensive use of the catheter than with relatively light catheter use. Twenty episodes were caused by a single bacterial strain and nine by multiple strains; coagulase negative staphylococci accounted for 51% of the strains isolated. Altogether 72% of infections were cured by antibiotic treatment, which was more likely to be successful in eradicating single than multiple infections. Although infection was common, mechanical problems were a more usual reason for catheter removal. There were no deaths caused by catheter related infection.