Background: Neurosurgical site infections result in prolonged hospitalisation and increased treatment costs. Cost of illness studies are important in computing the total costs of treatment of disease, as they quantify the burden of disease in terms of direct costs, productivity losses and intangible costs. Neurosurgical site infections do not occur at a high rate in most clinical settings. Their economic impact has been assumed to be minimal, and most studies have not exclusively studied their economic impact. Objective: To assess the economic burden of treatment of surgical site infections among trauma patients admitted at the neurosurgical ward of Kenyatta National Hospital. Methods: A prospective cost of illness study was conducted between April 2015 and June 2015 as part of a larger prospective cohort study. The patient perspective was adopted. The time horizon was the hospitalization period of the patients, which was a median of ten days. No discounting was done because the study was done within a year. A micro costing approach was used to compute direct costs on medication, laboratory and radiologic tests, cost of surgical procedures and nursing care, and direct non-medical costs incurred by patients for the average 10 day hospitalisation period. Productivity losses were also computed. Results: The total median cost of treating patients with neurosurgical site infections was higher, at USD 203.95 than that of patients without infection at USD 141.20. The median cost on antibiotics was USD 18.70 while that of non- antibiotic drugs was USD 33.03. The total median cost on laboratory and radiologic tests was USD 20 and USD 55 respectively. The key cost drivers were expenditures on meropenem, phenytoin, urea, electrolyte and creatinine tests and CT scans. With regards to costs of services, care-giver costs accounted for the highest median expenditure, followed by costs of surgery and nursing care. Conclusion: Neurosurgical site infections increase hospitalisation duration and costs. Prevention of these will reduce patient expenditure. Key words: cost of illness, neurosurgical site infection, productivity losse
