The incidence of S. aureus bacteraemia in a haemodialysis unit was studied over 2 years (167.75 patient-years of follow-up) during which nasal calcium mupirocin was used to eradicate nasal S. aureus carriage; this incidence was compared to that previously observed in the same unit before the use of nasal mupirocin (185.8 patient-years). Nasal mupirocin led to eradication of nasal S. aureus carriage in 96.3% of surveillance cultures and to a fourfold reduction in the incidence of S. aureus bacteraemia per patient-year, from 0.097 before mupirocin to 0.024 with mupirocin use (P = 0.008). Once or thrice weekly maintenance regimens of mupirocin were equally efficacious. The incidence of bacteraemia caused by other micro-organisms was not significantly affected. One single mupirocin-resistant isolate was identified in a nasal surveillance culture. Eradication of S. aureus from the nares did not lead to overgrowth by other micro-organisms. Chemoprophylaxis with nasal mupirocin in haemodialysis patients is cost-effective.