A chronic bacteraemia due to Staphylococcus epidermidis occurred in a patient undergoing allogeneic bone marrow transplantation. Forty-two S. epidermidis isolates were obtained from blood cultures over a period of 5 months. Isolates were separated into three groups by SmaI macrorestriction characterisation with pulsed-field gel electrophoresis (PFE-1, one isolate; PFE-2, 32 isolates; PFE-3, nine isolates). Differences were detected in antimicrobial susceptibility patterns among isolates belonging to group PFE-2. The two strains, PFE-2 and PFE-3, were both responsible for the chronic bacteraemia and were isolated during different admissions to the hospital. A central venous catheter was the portal of entry for PFE-2. DNA macro-restriction analysis with pulsed-field gel electrophoresis was helpful in the epidemiological investigation of this S. epidermidis chronic bacteraemia.