This is a report of necrotising subcutaneous infection in the perineum of three young girls with acute lymphoblastic leukaemia (ALL). This occurred during induction therapy when they were granulocytopenic. Pseudomonas aeroginosa was isolated from both blood and affected sites. With aggressive chemotherapy and extensive surgical debridement, two patients were salvaged but one perished from the septicaemia. Necrotizing Fasciitis is an uncommon progressive infection of the subcutaneous tissue. It occurs more frequently in adults following surgery or trauma and rarely arises spontaneously. In the paediatric literature, reports are few and mainly in healthy children occurring post-operatively. There was only one case of this occurring in a boy with Aplastic anaemia. Early recognition and aggressive therapy helps to improve the morbidity and mortality of this devastating condition.