Background: Elderly oncology population(EOP) corresponds to an increasing and heterogeneous group with high risk to infectious complications. Advances in antimicrobial therapy have not accompanied progress in cancer therapy. Identifying at admission the predictive factors for infection and death in the elderly population oncology is highly desirable for offering personalized care. Methods: Prospective cohort involving elderly people with cancer, followed by six months. At admission, evaluation of sociodemographic, clinical-laboratory and CGA variables. The outcomes studied were the first HAI and death. Multivariate Cox proportional hazards analysis identified risk factors for HAI and survival of patients with and without HAI by Kaplan-Meier was compared by the log rank test. Results: 605 patients were eligible, mean age 71.3 (SD ± 7.4). 29.1% developed HAI and 33.0% died during the study follow-up, 14.2% died within three weeks after the diagnosis of HAI. The risk factors for HAI were: risk of malnutrition / malnutrition by global nutritional assessment (MAN-global ≤ 23.5) (HR 2.18 95% CI 1.53-3.11); functional performance ≤ 50 by Karnofsky (HR 1.69 95% CI 1.14-2.50); severe renal dysfunction / final stage (HR 2.51 95% CI 1.37- 4.60).The topographies of the most frequent IRAS were urinary tract infection (UTI) (39.2%), pneumonia (22.7%) and bloodstream infection (14.8%). Minor survival among patients with HAI (log rank < 0.001). About half of those with pneumonia (50.0%) or ICS (46.2%) died within six months, with 30% and 23.1% of these deaths occurring within 21 days of the diagnosis of pneumonia or ICS, respectively. Conclusions: HAI represents a problem of high morbidity and mortality for EOP. Reduced renal function, risk of malnutrition and low functional performance were independent factors for HAI, significantly reducing the survival of elderly cancer patients. These aspects should be evaluated systematically in the admission of the elderly cancer patient and taken into account in the planning of the care to be offered.