The problem of cross-infection in a burns unit was recognized by Cruickshank (1935) when he described the acquisition of Streptococcus pyogenes in patients after admission to hospital. He also showed that the organism was frequently present in the air. Investigations into the spread of Str. pyogenes and later Staphylococcus aureus continued throughout and following the Second World War. In 1950 Colebrook, working in Birmingham, described the principles for preventing the spread of infection. He considered that a specialized centre with trained staff was necessary and proposed the following: (1) All dressing techniques should be done in clean air; (2) A strict aseptic technique, e.g., including masks, caps, gowns and overshoes, should be used; (3) Patients should be nursed whenever possible in properly designed cubicles; (4) Chemotherapy should be applied when changing dressings, depending on bacteriological findings, and dayto-day liaison should take place with the bacteriologist acting as ' Infection Control Officer'; (5) An operating theatre and anaesthetist should always be available so that skin grafts can be applied at the optimal time. These principles still apply today, but modifications of the techniques might be considered in relation to increased knowledge of the spread of organisms, particularly of Gram-negat ive bacilli. Cross-infection in a burns unit mainly occurs with Staph. aureus, Pseudomonas aeruginosa and other Gram-negat ive bacilli, such as Acinetobacter calcoaceticus var. anitratum. Aminoglycoside-resistant Ps. aeruginosa is a particular problem, limiting the choice of therapy in clinical infections. Staphylococcus aureus tend to spread widely in a unit, but are not usually a major clinical problem. Streptococcus pyogenes also cause occasional outbreaks and graft failure in individual patients, but can usually be controlled by therapy or prophylaxis with penicillin. These organisms spread by the airborne route or by direct or indirect