Admission to the ICU is often sudden and unexpected reflecting the serious and the frequently life-threatening conditions managed there in. For the patients, removal from home to unfamiliar surrounding can be distressing and disorienting. It is essential for health care professionals to be aware of sources of stress for individual patients so that they may attempt to prevent, or at least reduce them. The aim of the present work was to identify environmental stressors affecting patients in different ICUs of Alexandria hospitals, both from patients and nurses perspectives, and to investigate factors associated with the degree of patients' stress. A cross sectional approach was utilized. Five ICUs affiliated to 5 hospitals representing the administrative types of health care delivery systems in Alexandria were selected at random. Thirty adult patients were selected from each ICU with a total of 150 patients. All nurses working in the selected ICUs were also included. Patients' records were reviewed and a structured interview was utilized to collect data about personal, socio-demographic characteristics, type of stay in ICU, expenses coverage, illness-related information, and past history of admission to ICU. In addition, patients were asked about their perception of the stressors included in the Intensive Care Unit Environmental Stressors Scale [ICUESS]. For nurses' sample, self-administered questionnaire was used to obtain information about personal data, level of education, and training courses received. Nurses' opinion about the stressors affecting patients in the ICU was obtained using the same questions included in the ICUESS. Results showed that elderly patients [60 years or more] had significantly lower mean total stressor score compared to younger age groups. Patients in university and private hospitals had lower mean stressor score than those in other hospitals. Patients in the free and class degrees had significantly lower total stressor score than those in the unified degree. Also, patients whose expenses of stay in the ICU were covered by gratis or out of pocket had significantly lower total stressor score than those whose expenses were covered from insurance system. Results also revealed that the five stressors with the highest rating by patients were psychosocial. Nurses could correctly identify only one of the five most important stressors mentioned by the patients; which knows of the death of other patient. The mean rating of stressors to the patients from the nurses' point of view was higher than those reported by the patients for all the stressors. Critical care nurses, apart from maintaining their efforts to minimize the negative effects of the stressful critical care environment, needed to equally focus on the patients' psychological needs through measures in re-establishing patients' self-control and minimizing the emotional stress. Pre-employment and in-service training programs for nurses working in ICUs should be implemented.