The sepsis syndrome is the systemic response of the body to infection. It develops from the earliest stage, Systemic Inflammatory Response Syndrome sepsis, to severe sepsis, septic shock and multi-organ dysfunction syndrome. The incidence of sepsis is growing and globally accounts for one in ten admissions to Intensive Care Units. The mortality rate for severe sepsis ranges from 25% to 67%. People with cancer are ten times more likely to develop sepsis and having developed it have a higher mortality rate. Early recognition and treatment of sepsis has been demonstrated to improve outcomes. This study sought to improve early recognition of sepsis in cancer patients receiving acute treatment. Nurses and patient assessment were the focus of this study. The design was a prospective multi-method observational study with two interventions: a teaching session for 177 nurses; the introduction of a bedside test - Procalcitonin (PCT-Q), an immunological marker of sepsis. PCT has been shown to be a reliable marker of sepsis. The PCT-Q, has been used since the late 1990s but never by ward nurses. Methods used were: qualitative interviews of ten nurses and a questionnaire survey of 177 nurses pre and post intervention; and a patient database with the PCT-Q test being used 416 times in 320 patients to diagnose sepsis. The study showed that nurses and patients recognise the early changes of deterioration before their observations change. Nurses recognise these changes because they know their patients well. Nurses' knowledge improved in several areas during the study and they used PCT-Q appropriately, diagnosing sepsis at an early stage in 66% of cases. Ordinal multi-regression analysis demonstrated that PCT was more reliable than CRP and, used together with a low WBC and high lactate, accurately predicts sepsis.