Elderly patients account for 42-52% of intensive care unit (ICU) admissions and for almost 60% of all ICU days in the USA and up to 50% receive inappropriate antibiotic treatment. The aim of this study was to evaluate whether adherence to Standard Operating Procedures (SOPs) reduced ICU mortality in an elderly population. The study included consecutive patients (n = 228) aged > or = 60 years with an ICU stay of > 72 h. SOPs were based on evidence-based medicine guidelines for diagnosis and treatment of infections, and on local resistance rates. According to preset indicators of quality management standards and assessment of different degrees of adherence, an implementation rate > 70% was considered adherent (high adherence group [HAG]) and < or = 70% was considered non-adherent (low adherence group [LAG]). Patients in the HAG (n = 137) had significantly reduced mortality compared with LAG patients (n = 91): 5.8% versus 19.8%, respectively. It was concluded that adherence to SOPs based on evidence-based medicine that consider local resistance rates for antibiotic treatment in elderly ICU patients is associated with a lower mortality rate.