Introduction/background Nosocomial infections (NI)are a real public health problem, especially in intensive care units, where the risk of NI and death is higher, mainly when multidrug-resistant bacteria cause these infections. The objective of the present study was to determine the main risk factors for NI as well as the prognostic factors associated with the occurrence of death in adult intensive care units. Methods This is an unmatched case-control study, nested in the cohort of patients admitted to the intensive care unit of the medico-surgical emergencies of the Oran hospital and university hospital (Algeria), from June 3, 2012 to December 31, 2013.The cases (n=73) corresponded to patients who developed a NI and the controls (n=232) corresponded to those who were free from NI. The risk factors studied corresponded to exposures to the various invasive medical devices. To study the relationship between the different types of variables, the Chi-square test was used for the categorical variables and the Student test for the quantitative variables. The statistical significance level p has been set at 5%. Results In multifactorial analysis, male sex (aOR = 3,16, p = 0,03) and central venous catheterization duration greater than 8 days (aOR = 4,7, p = 0,01) were significantly associated with the occurrence of NI. The occurrence of death was associated with three prognostic factors, that is: age greater than 65 years (aOR = 4,31, p < 0,01), exposure to intubation (aOR = 9,49, p < 0,001) and the presence of central venous catheterization(aOR: 2,43, p = 0,02). The presence of NI regardless of its location was not associated with the occurrence of death. Conclusion Prolonged exposure to different invasive devices was the main risk factor for the development of NI in the intensive care unit. However, no significant associationwas found between the NI and the occurrence of death.