Nosocomial anemia is a common intensive care unit acquired complications that can lead to poor outcomes and increase morbidity and mortality. Critical care nurses should prevent it by identifying risk factors, minimizing factors contributing to it, using blood conservation strategies, and monitoring oxygen status and hematological one. Aim: The study aimed to assess factors affecting nosocomial anemia in hospitals among critically ill patients. Design: A descriptive exploratory research design was utilized in this study. Subjects: A purposive sample of (110) patients. Setting: This study was conducted in the Intensive Care Units at El-Fayoum General Hospital. Data collection tools: Tool (I) Patients' structured interview questionnaire: Part (I): Patients' demographic characteristics: Part (II): Patients' health related data. Tool (II): Factors affecting nosocomial anemia assessment Questionnaire: it included four parts: (I): Nutritional and fluid balance-related factors, (II): Drugs-related factors, (III): Sepsis - related factors and part (IV): Blood loss -related factors. Tool (III): Indicators of hospital acquired anemia it included (I): Hemodynamics parameters indicators and (II): Laboratory data. Results: The present study illustrated that less than two thirds of the studied patients had anemia on admission while, more than one third of them had nosocomial anemia. Conclusion: There was a highly statistically significant relation between the incidence of anemia and demographic characteristics (age, gender, educational level and length of hospital stay) among the studied patients. Recommendations: Provide adequate nutritional support considering the quantity and quality of requirements according to patient's condition and availability of dietitian inside critical care unit